It says "increasing speed in any direction", so increasing negatively counts, because the motion would just be going farther from the starting point in the opposite direction.
Yes, I agree with Nazia. In any direction specifies the fact that the object can be going quicker whether in the negative direction, or in the positive direction. If you took the extra step and graphed the position vs time graph, you would see that as time goes on, the object goes quicker and quicker in c and f. While in E and D, the object would be going slower and slower, coming to a stop.
Sorry, but that is incorrect. If they were position vs. time, it would be true, but it's velocity vs. time. This means that only straight lines are constant speeds and graphs with a slope greater than 0/(all real #'s) are accelerating.
Because Graphs A and B have a slope of 0, that means the velocity is 0. If the velocity is zero, that means it isn't going in a particular direction and a certain speed. I think it could still be constant, though, because staying at 0 is constant, like in an acceleration vs. time graph, it can be zero and constant.
But the velocity is not zero. The slope is zero, stating that the speed is constant and not accelerating. The velocity is in fact a postitive number, so a P vs. t graph would look like C. on the second set of graphs. Remember, velocity is not the same as position.
The most confusing part is remembering what each slope stands for (for position and velocity) and the difference between constant "slope" (a straight line) and constant "what-the-slope-means" (velocity or acceleration). -Kevin Meglathery
When it is a velocity v. time graph, the line must be horizontal for the speed to be constant. Any slope in a velocity vs. time graph is acceleration because if velocity is increasing, the object must be accelerating in either direction (depending on a - or + slope).
We should write them down anywhere where you and / or Mr. Crane can access them. Also @Alexis - Things may get clearer if you graph the Position vs. Time graphs from what we know the Velocity vs. Time graph illustrates on the paper. Remember the pattern - Parabola, Increasing or Decreasing constant slope (C,D,E,F), Constant line above 0 (A,B), then 0, 0,0, etc. Also, for C,D,E,F the slope of those lines represent the acceleration, which means that they can not be moving at a constant speed.
Yes, Larry, speed is not direction, so it would be increasing. A car goes from 0-60 MPH foward right? Next the same drive starts at zero and goes 0-60 MPH backwards. He is still increasing his speed, but in a different direction which is not part of Speed itself.
10 is asking for any change in speed, while number 11 is just an increase, the speed can decrease, the slope becomes lesser, and for increasing the slope becomes greater. (Hope that doesn't sound confusing) ~Thomas Black
No, decreasing slope=decreasing speed for distance vs. time graphs. Changing speed (#10) includes the "decreasing slope=decreasing speed graphs" E and F. Increasing (#11) does not. -Billy Potts
Nah Jason you are right. For the cars velocity to be increasing it doesn't matter whether you traveling in the positive or negative direction. The object is still increasing has an increasing velocity which is not effected by direction.
For questions #9-11, Is there a difference between how you read a position vs. time graph and a distance vs. time graph? -Billy Potts (forgot to put my name....)
It's early in the morning, so correct me if I'm wrong, but I think that the only difference between the two is direction because distance ignores it. -Kevin Meglathery
Kevin your right because you can't have a negative distance. I think that's why we normally stick to a position vs. time or a velocity vs. time graph in class.
I agree with you on that one because it just said "increasing speed in either direction". The speed is changing in E, but it is also increasing positively. Even when it becomes a full parabola, it will still be increasing, just in the negative direction.
No, because as in F, the speed and the object's distance from zero are decreasing(slope=speed becomes nearly a flat line at the end). -Billy Potts (Wrong place last time.....)
No, I was saying its not E or F. F is like E but is positive. I think its easier to read as decreasing and since they are reflections of each other I used it as an example. -Billy Potts
*To clarify: in a velocity vs. time graph speed=distance from zero. Moving toward zero in velocity vs. time is decreasing speed. ignore the part about "slope=speed becomes nearly a flat line at the end"
I am still a little confused so is F or E the answer i had put a few answers because they were increasing in either direction so i am not sure if what i had put was correct. Can someone explain to me if you are heading in the negative can you still be increasing spped even though you are not going upwards because he said either direction. -Ashley Lawler
Well, first of all, it can not be E at all. This is because of the simple reason that it is not increasing speed. It actually is decreasing speed. The object is travelling towards zero quicker from lets say 1-2 seconds than it is from 3-4 second mark. Eventually the car (if the graph continued) would be at a complete stop.
It just indicates a linear function, so it can be slanted, because that still means it's constant. When it's perpendicular to the y-axis, the slope is constant and 0 (not changing).
It definitely can be slanted because any linear function graphed is a straight line, which is considered constant. For example, x+6 (I know this isn't math class but still...) is a slanted line, but as long as there is no X^2 or X^3 etc.
But if you were to due 7, it would be E and F. Even though they have different points of origin, they are still both traveling in the negative direction constantly
No, #7 would be B because it is a Velocity vs. Time graph. It asks for a negative and constant velocity NOT slope. B's Velocity is negative and constant, while E and F are accelerating negatively at a constant rate. -Billy Potts
I think so, because if it was standing still there would not be any acceleration. Therefore, there would not be a straight line across the graph, instead there would just be a point on the graph and the starting position would not change -Kristina Bennett
it is B. for instance, if we were doing the buggy lab, and left the car alone, the line on the sensor would be the same as graph B because every time the sensor would receive data, the line would be a straight line because the distance is staying the same
If you think about 0 being the starting point and you look at the graph, over the course of time your position didn't increase or decrease at any point from 0, therefore there is no motion going on
Yes i agree with kyle the answer has to be B because if something is not in motion it means it is not moving. The horitizonal line remains the same throughtout time. Therefore there is no change and speed and the line remains the same.
The key word is "changing". When a graph is described as changing, it means it's parabolic. Changing in either direction just means that the graphs that qualify can be curved positively or negatively. Hope that clears it up for you!
Questions can't be stupid. But, I don't really know what your trying to ask.....
But for a changing speed in the graphs shown in for questions #9-11:
A changing speed for a distance vs. time graph is a parabola or otherwise has a changing(not constant) slope as slope=speed for distance vs. time graphs.
As we learned in class, the slope of a linear graph is the speed. Since any linear line has no change in slope, the speed is not changing. Then, all you do is see that if the graph is not linear, you have a change in speed
For #11 (increasing speed in either direction), E and F would not be plausible answers, right? The slope decreasing would mean the speed is decreasing too?
in these distance/time graphs, first we look for parabolas. All other graphs are ruled out because linear graphs have no change in slope or speed. Then, we eliminate the parabolas that are going to the x axis, because these are slowing down. We are left with A and D because they are parabolas (changing slope) going away from the x axis (increasing speed)
I believe that "E" would be possible because the starting point is negative and it ends around zero so it is increasing. Also, different circumstances could make the speed decrease when the slope does. In this case, yes, if slope was increasing than soo would speed. It would be the same in the opposite direction
Yes Mimi i did i am not sure if my answers are correct so i just checked here but i might check with Crane just to make sure i am doing it right and have any other questions.
Would graph F apply to number 10 even though it's changing speed by slowing down completely until it reaches 0? Or would it only just apply to graphs that are changing speed by increasing positively?
A wee bit paranoid with this... Number 14 asks for the graph with "decreasing speed toward the origin." The origin is where the x-axis and y-axis meet at (0,0). Is an answer possible here, or will it be none?
The wording for some of these questions got me very confused. It might mean that the velocity is lower at the origin than at the end of the graph, in which case I think that A and D would be answers. But if it means "which graph approaches the origin," then there wouldn't be an answer because time can't be negative. -Kevin Meglathery
Does the origin mean a position of zero? If so than E and F are the answers as they are decreasing speed toward zero.
I don't think A and D would be the answers, since that would be reading a graph backwards in time and it doesn't seem likely to have a real life application to cause it to be worded that way.
B and C have constant speeds so neither can be an answer.
So, I would say that E and F are the answers if origin means what I think it means, none if it doesn't, or A and D if its extraordinarily poorly worded.
I put that none of them were an option for the answer because the origin will always be (0,0). Like Kevin said, there's no such thing as negative time or going back in time, so none of the graphs are able to end toward the direction of the origin.
Billy Potts is correct in that E and F are the solutions because there is no such thing as increasing towards the origin. A parabola that goes towards the origin is always decreasing speed
Mr. Crane told us in class today that the bottom graphs should be Position v. Time, so I would agree that it's both B and C. Even though the position isn't changing, it's still constant with a positive slope of 0. C has a constant slope, but not motion. It still confuses me a bit, so please feel free to correct me if I'm wrong.
I asked Mr. Crane about this. He said that even though B isn't moving, it is still constant because it is constantly standing still. If you ask him about it, he will also explain why people who say it isn't constant are wrong. -Kevin Meglathery
I support Larry on this one. There are only two with a constant speed. B is ruled out because a horizontal line is not moving. The only thing increasing with a horizontal line is the time. There is no change in the y axis, therefore b is incorrect. C is constant because it is linear, and if you look at the y axis, you will see a change which indicates that it is moving. The correct answer is just C
No I believe it would only be c because that is moving at a constant speed while b is not moving at all it remains the same even though they are both constant
I'm pretty sure it wouldn't be G because #8 says "moving in the positive direction with a changing speed" which C is obviously doing. But I got it wrong so I don't know what the other would be. -Katie Cabrera
For anyone who is having trouble with number 5, the answer is not one of the options. This is because all of the graphs are velocity vs. time. Additionally, the only way that there would be an answer would be if there was basically no line visible, in otherwords, the line would be constant, horizontal, and on the zero line. In any other situation, the object would be moving.
I am not very good at this. For the velocity vs time graphs, the direction it is speeding up/slowing down in is only determined by where it starts and finishes in comparison to the y axis, right?
If I understand your question right, you almost got it. You really just have to look at zero. A straight line moving towards zero is slowing down because it is getting closer to zero, or a complete stop. With direction, you just have to look at whether it's above or below zero. If it started at 100 and got to .001, it is still moving in a positive direction. -Kevin Meglathery
I know the worksheet was already submitted, but just as a final question, If a line starts at 100 and goes to 0, was it still moving in a positive direction?
Yes. It was slowing down the entire time, but it was still going forward. Imagine going 100 mph on the highway. Now you just take your foot off the gas. As you slow down, you're still moving forward, aren't you? -Kevin Meglathery
Can someone tell me if this is the general set of rules for interpreting graphs? If it on the x axis, it is not moving. If it has a slope that is changing positively, it is speeding up. If it it has a slope that is changing negatively, it is slowing down. Direction is determined by where it starts and finishes in comparison to the y axis. is that all?
For the x-axis, it depends on what type of graph you're analyzing. If it has a slope increasing positively, it's speeding up, and if it has a slope increasing negatively, it's also speeding up. The graph would represent slowing down when it's decreasing positively or negatively (towards the x-axis). You are right about the direction, but it once again depends on what type of graph you're viewing.
If the line is constantly on the x-axis, then yes, it is standing still. The slope doesn't have to change positively; it has to increase. If the slope is positive but below zero, then the object is slowing down. Think of it this way: if you know something in the positive direction, mentally reflect it over the x-axis to see the same scenario in the negative direction. -Kevin Meglathery
We just continue to post here, so other students that haven't blogged yet can scroll through the feed and get a better understanding of some of the other graphs.
I think you're right about 13 Makena! I just put D for my answer, but it probably should be both A and D because they both have the same meaning, just different directions. It's all based on the point of reference. As for 12, I'm a little confused. I put D and E for my answer, but that's wrong too. If A, B and C obviously aren't moving in the negative direction, would that mean it's D, E and F? The analysis of E and F are what's confusing me.
Number 12 is looking for the graph(s) that are moving in the negative direction. The reason that it's F and not E (please correct me if I'm wrong) is that E starts negative and ends at zero, so it must be going in the positive direction. F starts positive but ends at zero, so it has to be moving in the negative direction. Or another way to look at it is that D and F both end at a point lower than the one they started at. -Kevin Meglathery
Your explanation really helps understand the graphs and situation better, Kevin, so thank you, but if Makena put D and F and got it wrong, that might mean there's another graph that relates to it. That's what confuses me a little.
I'm just going to state the obvious to make some sense of this problem.
We can all agree that A,B,and C are wrong and we should ignore them entirely. The answer "D,E" is wrong. The answer "D,F" is wrong. We can all agree that D is definitely an answer. That leaves the only possible answers "D" and "D,E,F." Now we just have to figure which one it is and why. But if Makena just misread her answer sheet and "D, F" is correct, then this whole post is kind of moot. -Kevin Meglathery
Number 13 has me rather confused. Mr. Crane said to use the strato-jump as an example. He also said that because the question did not specify a starting point, there is more than one answer. I know that D is correct because if you call the plane zero, then you increase speed in the negative direction until you hit the ground. I think that D is the only answer, but I'm really not sure. Any input? -Kevin Meglathery
I thought it would be just D too, but it obviously isn't because it was marked wrong on my answer sheet. I'm thinking that it's both A and D because they both describe the same motion, and based on the point of reference, it will tell you which direction the object is moving in. It has to be both because we don't know what the point of reference is, but we do know that it's accelerating and the slope is changing. By the way, your method of elimination really helped.
#12 is D and F. Mr. Crane told us in class that #12 is D and F. He just put the wrong letters in for that one.
#13 is A and D because D is correct if the acceleration of gravity is negative (and so the velocity of the object is increasing negatively). Likewise, A is correct if you call the acceleration of gravity positive (and so the velocity of the object is increasing positively).
Okay thanks Billy because that was the only conclusion I kept coming too and when Makena said hers was wrong it made me really confused.. But thanks Kevin for helping me realize why it would be D and F. -Katie Cabrera
Can anyone help me with number 8? I don't understand what the other answer would be because I have C already.. Can someone explain please? -Katie Cabrera
C is the obvious answer because it has a positive slope. But you have to remember about direction. In velocity v time graphs, above zero is the positive direction and below zero is negative. A, C, and E are the only graphs above zero, therefore the only ones moving in the positive direction. A is at a constant speed, so it can't be an answer. E is the other answer because although its slope is negative, it is still above zero. Graph E shows an object that is slowing down in the positive direction. -Kevin Meglathery
I don't agree with you on this one Kevin. #8 asks for a graph moving in the positive direction with a changing speed. That's the key word: CHANGING. When a graph's motion is changing, it would have to be a parabola, but all of the graphs are linear. Therefore, none of the graphs work for this situation, so it would be G.
Sorry guys, I didn't realize what type of graphs they were. Now it makes sense because velocity is the derivative of position. Therefore, where velocity is positive, position is increasing, aka moving in the positive direction. So, Kevin is right and the answers would be C and E.
Molly, E is the other answer. Because its slope is changing, then its speed is also changing. And because it's above zero, it has to be moving in the positive direction. Think of it this way. Imagine driving down the highway at 60 mph. Now just take your foot off the gas. You're still moving forward, but you're also changing speed. -Kevin Meglathery
can someone help me with #7? i had originally put D and F but everyone I've talked to said the correct answer is B but i don't understand how that is possible. ~Gianna Brilgia
Remember that constant speed would be a flat line. D and F are changing speed. B is the only correct answer because it's below zero (negative) and has a constant speed (horizontal line). -Kevin Meglathery
Number 4 is just asking for "moving in the negative direction." Because these are velocity v time graphs, anything below zero is negative, so the correct answers are B, D, and F. -Kevin Meglathery
For number 4, since it says moving in the negative direction, and it is a velocity vs. time graph, anything below zero is right, even if the line is moving towards zero -Andrew Nazha
Correct. Imagine flooring it while going in reverse, then taking your foot off the gas. You're slowing down, but you're still going backwards. -Kevin Meglathery
"Not moving" is a constant speed, but the key word in that question is "moving." While it does have a constant speed of zero, it isn't moving anywhere, so the only correct answer is B. -Kevin Meglathery
Number 5 is asking for the graphs that are standing still. Keep in mind that these are velocity v time graphs, so a flat line can be misleading. In order for one of these graphs to be standing still, the line would have to be on the x-axis, indicating no movement. Since none of the graphs show this, the correct answer is G.
Number 15 is just C. B and C are the only ones with constant speed (B with a constant speed of 0 and C with a positive constant speed.) However, because B's constant speed is zero, it isn't moving anywhere, so the only right answer would be C. -Kevin Meglathery
What would a freely falling object in a vacuum behave like? Since we are given distance-time graphs, all it has to do is be a parabola shooting away from the x axis correct?
Yeah you're right. When the vacuum is off, the object is at zero but when it turns on, the object shoots up positively with a changing speed -Andrew Nazha
pretty easy mr.crane when are we going to do some of the cool physics and not graph anymore, I think we've beat graphs to death. Toto.
ReplyDeleteOnce you know it.
DeleteWhat isn't cool about graphs?
DeleteAre you crazy? Physics is all about graphin and comparing data.
ReplyDeleteFor #2, does the increasing speed also include increasing negatively (decreasing)?
ReplyDeleteIt says "increasing speed in any direction", so increasing negatively counts, because the motion would just be going farther from the starting point in the opposite direction.
DeleteWould it be increasing speed if it stated below zero and went in the negative direction?
DeleteI guess it would because the velocity is still increasing, it just isn't increasing in the positive direction.
DeleteOk I read wrong. Thank You.
DeleteYes, I agree with Nazia. In any direction specifies the fact that the object can be going quicker whether in the negative direction, or in the positive direction. If you took the extra step and graphed the position vs time graph, you would see that as time goes on, the object goes quicker and quicker in c and f. While in E and D, the object would be going slower and slower, coming to a stop.
DeleteWhere did you say you wanted there questions written down? Our notebooks or just write it down on the paper?
ReplyDelete-Jake Naumann
He said our notebooks would be best.
Deletefor number 1 aren't they all constant? -alexis
DeleteYes for #1 they are all constant because the all have constant slopes
DeleteSorry, but that is incorrect. If they were position vs. time, it would be true, but it's velocity vs. time. This means that only straight lines are constant speeds and graphs with a slope greater than 0/(all real #'s) are accelerating.
DeleteBecause Graphs A and B have a slope of 0, that means the velocity is 0. If the velocity is zero, that means it isn't going in a particular direction and a certain speed. I think it could still be constant, though, because staying at 0 is constant, like in an acceleration vs. time graph, it can be zero and constant.
DeleteBut the velocity is not zero. The slope is zero, stating that the speed is constant and not accelerating. The velocity is in fact a postitive number, so a P vs. t graph would look like C. on the second set of graphs. Remember, velocity is not the same as position.
DeleteThat was my mistake there. I mixed up what the slope was, thinking it was velocity when it's really acceleration.
DeleteYeah, I'm not a fan of the velocity graphs. There tricky to interoperate.
DeleteSo much going on! I have to take a look at my notes for this all to make sense to me.
DeleteOk I see thanks. I read to quickly and Mike check your notes it will help.
DeleteThe most confusing part is remembering what each slope stands for (for position and velocity) and the difference between constant "slope" (a straight line) and constant "what-the-slope-means" (velocity or acceleration).
Delete-Kevin Meglathery
When it is a velocity v. time graph, the line must be horizontal for the speed to be constant. Any slope in a velocity vs. time graph is acceleration because if velocity is increasing, the object must be accelerating in either direction (depending on a - or + slope).
DeleteWe should write them down anywhere where you and / or Mr. Crane can access them. Also @Alexis - Things may get clearer if you graph the Position vs. Time graphs from what we know the Velocity vs. Time graph illustrates on the paper. Remember the pattern - Parabola, Increasing or Decreasing constant slope (C,D,E,F), Constant line above 0 (A,B), then 0, 0,0, etc. Also, for C,D,E,F the slope of those lines represent the acceleration, which means that they can not be moving at a constant speed.
DeleteYou are correct about the A and B being constant though. They are the only two that ARE constant. Everything else is not a contant speed.
ReplyDeleteOkay soooo what if the line is below zero and moving in a negative direction. Would that mean the speed is still increasing? HELP ME
ReplyDelete-Larry G
Yes. It says increasing speed in either direction (#2). The speed is increasing in a negative direction so yes.
Delete-Billy Potts
Yes, Larry, speed is not direction, so it would be increasing. A car goes from 0-60 MPH foward right? Next the same drive starts at zero and goes 0-60 MPH backwards. He is still increasing his speed, but in a different direction which is not part of Speed itself.
DeleteWhat is the difference between #10 (Changing speed in either direction) and #11 (increasing speed in either direction)?
ReplyDelete-Billy Potts
10 is asking for any change in speed, while number 11 is just an increase, the speed can decrease, the slope becomes lesser, and for increasing the slope becomes greater. (Hope that doesn't sound confusing)
Delete~Thomas Black
Okay. Thanks.
DeleteIt makes sense now.
-Billy Potts
Wouldn't increasing in either direction be increasing positively AND negatively? So really #10 and #11 would be the same question?
DeleteNo, decreasing slope=decreasing speed for distance vs. time graphs. Changing speed (#10) includes the "decreasing slope=decreasing speed graphs" E and F. Increasing (#11) does not.
Delete-Billy Potts
Nah Jason you are right. For the cars velocity to be increasing it doesn't matter whether you traveling in the positive or negative direction. The object is still increasing has an increasing velocity which is not effected by direction.
DeleteTaylor is correct. A car going from 0-60 in reverse is still increasing speed, while a car going 0-60 foward is increasing speed too.
DeleteFor questions #9-11, Is there a difference between how you read a position vs. time graph and a distance vs. time graph?
ReplyDeleteFor questions #9-11, Is there a difference between how you read a position vs. time graph and a distance vs. time graph?
Delete-Billy Potts
(forgot to put my name....)
I don't think there is a difference. I read it as position vs. time.
DeleteThe only difference would be what the slope stands for. Otherwise, I don't think there's a difference in how you read it, either.
DeleteThat's what I did too.
DeleteI normally think of them as the same type of graph.
DeleteIt's early in the morning, so correct me if I'm wrong, but I think that the only difference between the two is direction because distance ignores it.
Delete-Kevin Meglathery
Kevin I dont think that it matters because position doesnt have direction, but the change in position which is displacement does.
DeleteKevin your right because you can't have a negative distance. I think that's why we normally stick to a position vs. time or a velocity vs. time graph in class.
DeleteFor number 11, I believe "e" is an answer. Does anyone care to concur?
ReplyDeleteI agree with you on that one because it just said "increasing speed in either direction". The speed is changing in E, but it is also increasing positively. Even when it becomes a full parabola, it will still be increasing, just in the negative direction.
DeleteNo, because as in F, the speed and the object's distance from zero are decreasing(slope=speed becomes nearly a flat line at the end).
Delete-Billy Potts
(Wrong place last time.....)
I see what you're saying and that makes sense. It clears up some things, too!
DeleteWait I'm still confused because I thought it was E too. I don't understand completely how it's F.
DeleteNo, I was saying its not E or F. F is like E but is positive. I think its easier to read as decreasing and since they are reflections of each other I used it as an example.
Delete-Billy Potts
*Sorry, slope=/=speed
Deleteslope=acceleration in a V vs. T graph
-Billy Potts
*To clarify:
Deletein a velocity vs. time graph speed=distance from zero.
Moving toward zero in velocity vs. time is decreasing speed.
ignore the part about "slope=speed becomes nearly a flat line at the end"
Confusing Physics terms.....
-Billy Potts
Ignore the *To clarify and *Sorry slope=/= speed
DeleteConfused myself again............
I was right the 1st time.
-Billy Potts
I am still a little confused so is F or E the answer i had put a few answers because they were increasing in either direction so i am not sure if what i had put was correct. Can someone explain to me if you are heading in the negative can you still be increasing spped even though you are not going upwards because he said either direction.
Delete-Ashley Lawler
No, I was saying that it is not E and it is not F.
DeleteF is like E but is positive.
Usually (to me) is easier to understand as not "increasing in either direction" from a positive standpoint.
And since they are reflections of each other I used it as an example.
Decreasing Slope=Decreasing Speed for a distance vs. time graph.
-Billy Potts
Well, first of all, it can not be E at all. This is because of the simple reason that it is not increasing speed. It actually is decreasing speed. The object is travelling towards zero quicker from lets say 1-2 seconds than it is from 3-4 second mark. Eventually the car (if the graph continued) would be at a complete stop.
DeleteWhen a graph says it is constant does that always indicate a liner line that is perpendicular to the y-axis or can it be slanted?
ReplyDeleteIt just indicates a linear function, so it can be slanted, because that still means it's constant. When it's perpendicular to the y-axis, the slope is constant and 0 (not changing).
DeleteIt definitely can be slanted because any linear function graphed is a straight line, which is considered constant. For example, x+6 (I know this isn't math class but still...) is a slanted line, but as long as there is no X^2 or X^3 etc.
DeleteNo,because as in F, the speed and its distance from zero are decreasing(slope=speed becomes nearly a flat line at the end).
ReplyDelete-Billy Potts
Would graph e be 7? (Moving in the negative direction at a constant speed)
ReplyDelete-Erin V
We only needed to do 1-3 and 9-11. We might do more later, but only thoe 6 for right now.
Delete-Kevin Meglathery
But if you were to due 7, it would be E and F. Even though they have different points of origin, they are still both traveling in the negative direction constantly
DeleteNo, #7 would be B because it is a Velocity vs. Time graph. It asks for a negative and constant velocity NOT slope. B's Velocity is negative and constant, while E and F are accelerating negatively at a constant rate.
Delete-Billy Potts
didn't realize it was a velocity time graph until class, thought it was position
DeleteFor number 9 would the answer be none? Because its still in B is still in motion?
ReplyDeleteI think so, because if it was standing still there would not be any acceleration. Therefore, there would not be a straight line across the graph, instead there would just be a point on the graph and the starting position would not change
Delete-Kristina Bennett
It is a distance vs time graph, so B is not moving it, has a speed of zero (standing still)
Deleteit is B. for instance, if we were doing the buggy lab, and left the car alone, the line on the sensor would be the same as graph B because every time the sensor would receive data, the line would be a straight line because the distance is staying the same
DeleteIf you think about 0 being the starting point and you look at the graph, over the course of time your position didn't increase or decrease at any point from 0, therefore there is no motion going on
DeleteOkay, thank you for the clarification!
Delete-Kristina Bennett
Yes i agree with kyle the answer has to be B because if something is not in motion it means it is not moving. The horitizonal line remains the same throughtout time. Therefore there is no change and speed and the line remains the same.
DeleteIs it possible for a graph to stand still? I know people have asked this question already but I'm confused...
ReplyDeleteSorry, I really don't know what question your trying to ask....
Delete-Billy Potts
By stand still to you mean not changing? If so, I would guess that it would be a horizontal line, which means it stays the same with a slope of 0.
DeleteA horizontal line only increases in time. If you look at the y axis only, you will see that there is no change at all.
DeleteProbably stupid question but how would you show changing speed in different directions? Sorry if i repeated i am just confused.
ReplyDeleteThe key word is "changing". When a graph is described as changing, it means it's parabolic. Changing in either direction just means that the graphs that qualify can be curved positively or negatively. Hope that clears it up for you!
DeleteQuestions can't be stupid. But, I don't really know what your trying to ask.....
DeleteBut for a changing speed in the graphs shown in for questions #9-11:
A changing speed for a distance vs. time graph is a parabola or otherwise has a changing(not constant) slope as slope=speed for distance vs. time graphs.
-Billy Potts
As we learned in class, the slope of a linear graph is the speed. Since any linear line has no change in slope, the speed is not changing. Then, all you do is see that if the graph is not linear, you have a change in speed
DeleteFor #11 (increasing speed in either direction), E and F would not be plausible answers, right? The slope decreasing would mean the speed is decreasing too?
ReplyDeleteYes, you are correct. The velocity line is moving toward zero, so the speed is decreasing.
Delete-Billy Potts
*Confusing myself again.....
DeleteYour right.
Slope decreasing=speed decreasing (for distance vs. time)
-Billy Potts
in these distance/time graphs, first we look for parabolas. All other graphs are ruled out because linear graphs have no change in slope or speed. Then, we eliminate the parabolas that are going to the x axis, because these are slowing down. We are left with A and D because they are parabolas (changing slope) going away from the x axis (increasing speed)
DeleteI believe that "E" would be possible because the starting point is negative and it ends around zero so it is increasing. Also, different circumstances could make the speed decrease when the slope does. In this case, yes, if slope was increasing than soo would speed. It would be the same in the opposite direction
ReplyDeleteMoving toward zero in velocity vs. time is decreasing.
Delete-Billy Potts
Sorry, mixed-up explanation
Deletedecreasing slope(graph becomes almost flat line at end)=decreasing speed
So E and F CANNOT be increasing speed in either direction
-Billy Potts
I understand now. Thanks.
DeleteKevin said in a different post that if you know something positive, reflect that situation over the x axis to get how it would behave negatively
DeleteDid anyone get about 4 graphs for a few of them?
ReplyDeleteYes Mimi i did i am not sure if my answers are correct so i just checked here but i might check with Crane just to make sure i am doing it right and have any other questions.
Deleteyes
DeleteI only got 4 graphs for problem 10
DeleteWould graph F apply to number 10 even though it's changing speed by slowing down completely until it reaches 0? Or would it only just apply to graphs that are changing speed by increasing positively?
ReplyDeleteI believe it would.
ReplyDeleteA wee bit paranoid with this... Number 14 asks for the graph with "decreasing speed toward the origin." The origin is where the x-axis and y-axis meet at (0,0). Is an answer possible here, or will it be none?
ReplyDeleteYes hope an answer is possible the two graphs that end on the origin are correct.
DeleteThe wording for some of these questions got me very confused. It might mean that the velocity is lower at the origin than at the end of the graph, in which case I think that A and D would be answers. But if it means "which graph approaches the origin," then there wouldn't be an answer because time can't be negative.
Delete-Kevin Meglathery
Yes look at which graphs they are and read the question carefully becuase some trick you.
DeleteDoes the origin mean a position of zero? If so than E and F are the answers as they are decreasing speed toward zero.
DeleteI don't think A and D would be the answers, since that would be reading a graph backwards in time and it doesn't seem likely to have a real life application to cause it to be worded that way.
B and C have constant speeds so neither can be an answer.
So, I would say that E and F are the answers if origin means what I think it means, none if it doesn't, or A and D if its extraordinarily poorly worded.
-Billy Potts
I put that none of them were an option for the answer because the origin will always be (0,0). Like Kevin said, there's no such thing as negative time or going back in time, so none of the graphs are able to end toward the direction of the origin.
DeleteBilly Potts is correct in that E and F are the solutions because there is no such thing as increasing towards the origin. A parabola that goes towards the origin is always decreasing speed
DeleteWould #15 be both B and C.
ReplyDeleteI think it would be just C. The question says that the graph has to be moving. B is not moving at all, even though its speed is constant.
DeleteMr. Crane told us in class today that the bottom graphs should be Position v. Time, so I would agree that it's both B and C. Even though the position isn't changing, it's still constant with a positive slope of 0. C has a constant slope, but not motion. It still confuses me a bit, so please feel free to correct me if I'm wrong.
DeleteOk thats what I thought. Thanks.
DeleteI asked Mr. Crane about this. He said that even though B isn't moving, it is still constant because it is constantly standing still. If you ask him about it, he will also explain why people who say it isn't constant are wrong.
Delete-Kevin Meglathery
I support Larry on this one. There are only two with a constant speed. B is ruled out because a horizontal line is not moving. The only thing increasing with a horizontal line is the time. There is no change in the y axis, therefore b is incorrect. C is constant because it is linear, and if you look at the y axis, you will see a change which indicates that it is moving. The correct answer is just C
DeleteNo I believe it would only be c because that is moving at a constant speed while b is not moving at all it remains the same even though they are both constant
ReplyDeleteDid anyone just get D for #13?
ReplyDeleteI talked to Mr. Crane about that one today, and he said it could be A or D, depending on what your point of reference is.
DeleteFor anyone who is having trouble with #8, the answer is G. None of the above. There is no correct answer.
ReplyDeleteI thought C and E would work for the answer because they are in the positive direction and show a change.
Delete-Robyn Kimmel
I'm pretty sure it wouldn't be G because #8 says "moving in the positive direction with a changing speed" which C is obviously doing. But I got it wrong so I don't know what the other would be.
Delete-Katie Cabrera
For anyone who is having trouble with number 5, the answer is not one of the options. This is because all of the graphs are velocity vs. time. Additionally, the only way that there would be an answer would be if there was basically no line visible, in otherwords, the line would be constant, horizontal, and on the zero line. In any other situation, the object would be moving.
ReplyDeleteI am not very good at this. For the velocity vs time graphs, the direction it is speeding up/slowing down in is only determined by where it starts and finishes in comparison to the y axis, right?
ReplyDeleteIf I understand your question right, you almost got it. You really just have to look at zero. A straight line moving towards zero is slowing down because it is getting closer to zero, or a complete stop. With direction, you just have to look at whether it's above or below zero. If it started at 100 and got to .001, it is still moving in a positive direction.
Delete-Kevin Meglathery
I wasn't here the other day, so could anyone from period 4 explain to me what I missed? I would be very grateful.
ReplyDeleteDo the entire worksheet with the graph questions on it.
Delete~Thomas Black
John you will get a scantron in class tomorrow and you just need to shade in the answers.
DeleteThanks guys.
DeleteDing!
ReplyDeleteI know the worksheet was already submitted, but just as a final question, If a line starts at 100 and goes to 0, was it still moving in a positive direction?
ReplyDeleteYes. It was slowing down the entire time, but it was still going forward. Imagine going 100 mph on the highway. Now you just take your foot off the gas. As you slow down, you're still moving forward, aren't you?
Delete-Kevin Meglathery
Thanks Kevin. One more thing; how do you tell if it is speeding up or slowing down? Is it just if it has a positive or negative slope?
ReplyDeletePretty much, yes. Whether the slope is increasing positively or negatively, the object is speeding up.
DeleteCan someone tell me if this is the general set of rules for interpreting graphs?
ReplyDeleteIf it on the x axis, it is not moving. If it has a slope that is changing positively, it is speeding up. If it it has a slope that is changing negatively, it is slowing down. Direction is determined by where it starts and finishes in comparison to the y axis. is that all?
For the x-axis, it depends on what type of graph you're analyzing. If it has a slope increasing positively, it's speeding up, and if it has a slope increasing negatively, it's also speeding up. The graph would represent slowing down when it's decreasing positively or negatively (towards the x-axis). You are right about the direction, but it once again depends on what type of graph you're viewing.
DeleteIf the line is constantly on the x-axis, then yes, it is standing still.
DeleteThe slope doesn't have to change positively; it has to increase. If the slope is positive but below zero, then the object is slowing down.
Think of it this way: if you know something in the positive direction, mentally reflect it over the x-axis to see the same scenario in the negative direction.
-Kevin Meglathery
Thank you so much
ReplyDeleteShould we continue to post here for the "second try" at the take home quiz or will there be a separate thread?
ReplyDeleteWe just continue to post here, so other students that haven't blogged yet can scroll through the feed and get a better understanding of some of the other graphs.
DeleteYes and Rich explain how you got #4 is it because it starts in a negative on the y axis?
ReplyDeleteYes
DeleteNope, this is it.
ReplyDeleteis #6 not g because it could be E,F because one i heading towards 0 and the other is going away from 0
ReplyDeleteNo its D,E. This is because they are the only ones going towards the 0 line, otherwise getting slower.
DeleteOk thanks i forgot about d and f is not goin towards the 0 line.
ReplyDeleteFor 10 could it be all of them?
ReplyDeleteYes, it is.
DeleteOk i see why it is now
DeleteDid anyone get number 15 right? If so, what is the answer and why?
ReplyDelete#15 coulc be C because it has a constant speed and B is just standing still while time goes on. Do you agree Rich?
DeleteWold #12 right? Please explain.
DeleteThe key word in 15 is "moving". It would be just C because Graph B is standing still and not changing position at a constant speed.
DeleteI received a 10/15 but I have no idea which 5 I got wrong.
ReplyDeleteI am confused with number 12. Why isn't it D and F (or am I missing a letter?)and number 13 is still a little confusing to me. Is it A and D?
ReplyDelete~Makena
I think you're right about 13 Makena! I just put D for my answer, but it probably should be both A and D because they both have the same meaning, just different directions. It's all based on the point of reference. As for 12, I'm a little confused. I put D and E for my answer, but that's wrong too. If A, B and C obviously aren't moving in the negative direction, would that mean it's D, E and F? The analysis of E and F are what's confusing me.
DeleteThank you Nazia. I am still confused about 12 though.
Delete~Makena
Number 12 is looking for the graph(s) that are moving in the negative direction. The reason that it's F and not E (please correct me if I'm wrong) is that E starts negative and ends at zero, so it must be going in the positive direction. F starts positive but ends at zero, so it has to be moving in the negative direction. Or another way to look at it is that D and F both end at a point lower than the one they started at.
Delete-Kevin Meglathery
Your explanation really helps understand the graphs and situation better, Kevin, so thank you, but if Makena put D and F and got it wrong, that might mean there's another graph that relates to it. That's what confuses me a little.
DeleteI'm just going to state the obvious to make some sense of this problem.
DeleteWe can all agree that A,B,and C are wrong and we should ignore them entirely.
The answer "D,E" is wrong.
The answer "D,F" is wrong.
We can all agree that D is definitely an answer. That leaves the only possible answers "D" and "D,E,F."
Now we just have to figure which one it is and why. But if Makena just misread her answer sheet and "D, F" is correct, then this whole post is kind of moot.
-Kevin Meglathery
Number 13 has me rather confused. Mr. Crane said to use the strato-jump as an example. He also said that because the question did not specify a starting point, there is more than one answer. I know that D is correct because if you call the plane zero, then you increase speed in the negative direction until you hit the ground. I think that D is the only answer, but I'm really not sure. Any input?
Delete-Kevin Meglathery
I thought it would be just D too, but it obviously isn't because it was marked wrong on my answer sheet. I'm thinking that it's both A and D because they both describe the same motion, and based on the point of reference, it will tell you which direction the object is moving in. It has to be both because we don't know what the point of reference is, but we do know that it's accelerating and the slope is changing. By the way, your method of elimination really helped.
Delete#12 is D and F. Mr. Crane told us in class that #12 is D and F. He just put the wrong letters in for that one.
Delete#13 is A and D because D is correct if the acceleration of gravity is negative (and so the velocity of the object is increasing negatively). Likewise, A is correct if you call the acceleration of gravity positive (and so the velocity of the object is increasing positively).
-Billy Potts
Okay thanks Billy because that was the only conclusion I kept coming too and when Makena said hers was wrong it made me really confused.. But thanks Kevin for helping me realize why it would be D and F.
Delete-Katie Cabrera
Thank you, Billy! That really clears up a lot!
DeleteD, F are the only two moving towards the negative direction therefore they have to be the correct answer
DeleteIm confused with number 14? I don't know how to get the answer. Can anybody help?
ReplyDelete#14
DeleteDisplacement vs. Time Graph
decreasing slope(line becomes almost a flat horizontal line at end)=decreasing speed/velocity.
Both E and F are the only ones with decreasing slopes(velocities) and they are both moving toward zero/origin.
Thus, E and F are the answers.
-Billy Potts
So instead of the origin, I'm guessing Mr. Crane meant to say 0 or the x-axis since the origin is (0,0). Thanks so much!
DeleteCan anyone help me with number 8? I don't understand what the other answer would be because I have C already.. Can someone explain please?
ReplyDelete-Katie Cabrera
C is the obvious answer because it has a positive slope. But you have to remember about direction. In velocity v time graphs, above zero is the positive direction and below zero is negative. A, C, and E are the only graphs above zero, therefore the only ones moving in the positive direction. A is at a constant speed, so it can't be an answer. E is the other answer because although its slope is negative, it is still above zero. Graph E shows an object that is slowing down in the positive direction.
Delete-Kevin Meglathery
I don't agree with you on this one Kevin. #8 asks for a graph moving in the positive direction with a changing speed. That's the key word: CHANGING. When a graph's motion is changing, it would have to be a parabola, but all of the graphs are linear. Therefore, none of the graphs work for this situation, so it would be G.
DeleteI don't agree with you on this one either. They're velocity v time graphs, not displacement.
Delete-Kevin Meglathery
I believe C is correct but confused about what the other answer is. Nazia I dont think it would be a parabola because it is a velocity vs time graph.
DeleteSorry guys, I didn't realize what type of graphs they were. Now it makes sense because velocity is the derivative of position. Therefore, where velocity is positive, position is increasing, aka moving in the positive direction. So, Kevin is right and the answers would be C and E.
DeleteMolly, E is the other answer. Because its slope is changing, then its speed is also changing. And because it's above zero, it has to be moving in the positive direction. Think of it this way.
DeleteImagine driving down the highway at 60 mph. Now just take your foot off the gas. You're still moving forward, but you're also changing speed.
-Kevin Meglathery
These posts really helped me! Thanks everyone.
ReplyDelete- Catherine Samara
can someone help me with #7? i had originally put D and F but everyone I've talked to said the correct answer is B but i don't understand how that is possible.
ReplyDelete~Gianna Brilgia
Remember that constant speed would be a flat line. D and F are changing speed. B is the only correct answer because it's below zero (negative) and has a constant speed (horizontal line).
Delete-Kevin Meglathery
oh ok I was thinking that D and F were changing at a constant speed and that B just wasn't moving at all. Thanks!
Delete~ Gianna Briglia
Van anybody help me with number4 and thanks for the help i needed in number 14.
ReplyDeleteNumber 4 is just asking for "moving in the negative direction." Because these are velocity v time graphs, anything below zero is negative, so the correct answers are B, D, and F.
Delete-Kevin Meglathery
For number 4, since it says moving in the negative direction, and it is a velocity vs. time graph, anything below zero is right, even if the line is moving towards zero
Delete-Andrew Nazha
Correct. Imagine flooring it while going in reverse, then taking your foot off the gas. You're slowing down, but you're still going backwards.
Delete-Kevin Meglathery
can someone explain why b isnt also for #15? Not moving at all is still a constant speed right ?
ReplyDelete"Not moving" is a constant speed, but the key word in that question is "moving." While it does have a constant speed of zero, it isn't moving anywhere, so the only correct answer is B.
Delete-Kevin Meglathery
What did you guys get for number 5 and 15?
ReplyDelete-Matt Nazha
Number 5 is asking for the graphs that are standing still. Keep in mind that these are velocity v time graphs, so a flat line can be misleading. In order for one of these graphs to be standing still, the line would have to be on the x-axis, indicating no movement. Since none of the graphs show this, the correct answer is G.
DeleteNumber 15 is just C. B and C are the only ones with constant speed (B with a constant speed of 0 and C with a positive constant speed.) However, because B's constant speed is zero, it isn't moving anywhere, so the only right answer would be C.
-Kevin Meglathery
What would a freely falling object in a vacuum behave like? Since we are given distance-time graphs, all it has to do is be a parabola shooting away from the x axis correct?
ReplyDeleteYeah you're right. When the vacuum is off, the object is at zero but when it turns on, the object shoots up positively with a changing speed
Delete-Andrew Nazha
I missed class today. Can someone tell me what I missed?
ReplyDelete