Friday, January 11, 2013

AP:CH7:Impulse & Momentum

Solution to 23,39

15 comments:

  1. Which number are we supposed to stop at? 57?

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  2. Are we going over the problems in class? If not, could I please ask for some direction on #39... not sure if we need to use the equation for centripetal motion

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  3. yeah, most of the 30's confused me too

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  4. I didn't understand the questions when we got down to the 30's and for number 23, what equation are we supposed to use? I used m1v1 + m2v2 = (m1 + m2) v1,2. But when I plugged the numbers in, it wasn't the same as the back of the book.

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  5. For number 33 with the two cars or trucks, I understood part a), but for part b) I think they wanted the impulse immediately after the collision and I didn't know what equation to use. I know to start with m delta v = momentum, but I'm not sure whether to use inelastic or elastic collision.

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  6. I was just going through problems i didn't understand and for number 41, with the center of mass, I found the equation at the end of the chapter but I don't know what you plug in for the distances. Do you just plug in the same distance they gave you for both the variables? Or is that something we have to solve for?

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    1. I think that one distance, or x would be zero and then the other x2 would be the distance given. The way I thought of it was that one object is the starting point or zero and then there is x final or the distance from the starting point. Hopefully that helps!

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    2. Ohhh gotcha. I was cutting the distance given in half and plugging that in for both of them. Thanks!

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  7. The midterm review link only leads to an error page. Is anyone is getting this, or is it just me?

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    1. Probably not what you wanted to hear, but mine is opening. Make sure you click the most recent link.

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    2. make sure ur not copying where it says APB 1-25 review with the link because i copied and pasted that with the link and it gave me an error.

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  8. This comment has been removed by the author.

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  9. for question # 19 for my answes i got 38.97 and 22.5 which are exactly half of what the answers should be according to the back of the book. does anyone know why that might be? i did x/45=cos30 and x/45=cos60

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    1. The rockets are broken up into two equal pieces so the masses are each m/2. MAybe you forgot to multiply that 2?

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