Wednesday, May 29, 2013

Phreshman Human Power Lab

Height of 1bleacher= .21m
Does the horizontal distance matter? Why or why not?
How many calories did you burn going up once?


45 comments:

  1. I don't think the horizontal distance matters because it does not have an effect on how fast you climb the stairs.
    -Skylar Young

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    1. No it doesn't, because Mr. Crane said to me that I won't be able to tell the difference if he takes an elevator or the stairs, as long as he gets to the same position.

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    2. Yes its just like ignoring the velocity of the river in that polar bear problem we did

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    3. Yes Thomas as long as you get from point a to point b it doesn't matter. the fastest way to get somewhere is a straight line.

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  2. The horizontal distance does not matter because when finding the power, you dont need the width, you need the height. Also is that lab worksheet homework?
    ~Katie Cabrera MOD 3

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    1. Katie for the lab worksheet some classes had to do the first page of the worksheet. I am not sure what your class had to do but I would definitely do the first page just incase.

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    2. Yes, Katie, our homework is to finish up the lab worksheet, front and back.

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  3. for the worksheet. what is a kilo-watt-hour

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    1. i think it is 1000 watts per hour

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    2. That's how your home electricity use is measured. If you left a 100 watt light bulb on for ten hours, it would be one kilo-watt-hour.
      -Kevin Meglathery

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  4. for the first page in the packet how are we supposed to do the backpack thing if we dont have a spring scale?

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    1. I would assume that we don't need the actual measurements because the purpose of that question is to make sure that you know where the work and power are.

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  5. Is energy the same thing as power?

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    1. They aren't the same thing, but they are related, just like work is related to power. Work creates power and power generates and gives off energy.

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  6. This comment has been removed by the author.

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  7. The horizontal distance does not matter because you are getting to the same height whether you go straight up or diagonally

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  8. The horizontal distance does not matter much because our momentum is already heading horizontally. The horizontal distance DOES matter, but by so little that we can factor it out without our results being skewed. If we ran 3 meters, horizontally, we are definitely doing work. Also, I burned .41 calories running up the stairs.

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    1. What would the force be IF horizontal distance mattered, since the acceleration in our case was gravity?

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  9. Our class did not get to run the bleachers and we were told to run stairs for homework. Is there a specific amount or method that we have to use or should we just climb any amount of stairs and determine the calories?

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    1. Any amount of stairs is fine, because you'll still be generating a similar amount of work. The bleachers we ran were 13 stairs if you want to base it off of that, but it doesn't matter, because you are calculating the amount of work you get done in a certain amount of time. Distance is the dependent variable in the scenario, so it doesn't matter how it varies.

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  10. Horizontal distance doesn't matter because it's its own vector, and it doesn't "interact" with the vertical distance. We were climbing a vertical distance up the bleachers, against gravity, and that played a role in how much time it took for us to get to the top as well as how much work we did.

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  11. Is work a scalar because we are looking at the magnitude of it only?

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    1. Although Work is the product of two vectors (Force and Distance) it is a scalar. Think about it, you can't really have negative work, or undo work. It has no direction. Also, work is a change in energy, and because energy is a scalar (no negative energy), work, too, is a scalar.

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    2. No, the horizontal distance should not matter because you are still climbing the steps at an unchanged speed.
      Erin V

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    3. Wait, if the net work turned out to be zero, and the independent person did work, that means that the force of gravity applies work to cancel it out, making it negative. Negative means in the opposite direction, so could work be a vector?

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    4. I'm pretty sure Tom is right. Work is a vector for exactly the reason he said; gravity works down, and we counteract it by working up.
      -Kevin Meglathery

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  12. One horse-power equals about 746 watts, correct? And what does one Crane-power equal? I would like to see how I compare to both of them.
    -Kevin Meglathery

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  13. Should we put the answer for the last problem on the worksheet in amount of steps or centimeters?

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  14. The horizontal distance does not matter because we are only doing work against gravity.

    I burned .444 calories doing work against gravity.

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  15. I wonder if in another scenario, work can be done horizontally.

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    1. A similar example of work to our lab would be pushing a magnet toward a wall that repels it (or pulling a magnet away from a wall that attracts it) because when you let go it will accelerate in the opposite direction you are moving it, like gravity.

      [So in Work=F*D the force would be how much the two magnets (the magnet & the wall) repel/attract each other (& the displacement is the displacement)]

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  16. Push a bowling ball across a table in a physics room.
    -Kevin Meglathery

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    1. Also, I burned .4476 calories on one trip up the bleachers.
      -Kevin Meglathery

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    2. What would the force be because the force was our weight in the lab as we were doing work against gravity? So we did work horizontally in our lab as well?!???

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    3. Technically speaking, I guess we didn't. Because there was no force acting against us in the horizontal direction, we didn't do any work because there was no force to overcome.
      I thought we might have, because we obviously did something in order to move from the front of the bleachers to the back.
      So, to be perfectly honest, I'm not sure what the right answer is.
      -Kevin Meglathery

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    4. Our class ended up calculating the force using the original formula, F=ma. You plug in your mass in kilograms from the scale and 9.8 would be the acceleration because of gravity.

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    5. But, we did it against friction and air resistance, right?

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    6. We did, but we disregarded for the most part because it was a negligible amount.

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  17. What if there is no gravity, will the horizontal work be much larger?

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  18. I was absent for the lab so can somebody give me their data so I can do the work sheet and make sure im doing it correctly?
    Taylor Nardone

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  19. Does anyone know where the test is??
    -Catherine Samara

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    1. The Work Energy Power one is right under the headline Work Energy Power. it says it in grey and you click on that

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