TBR Physics ?s: section 1 and 2

[Pamplemousse123]

---

Members don't see this ad.

Hey there!

I have a question about question 11, passage 2 from the first section questions on page 37 and question 49, passage 7 from the second section questions on page 113.

Question 11 is about how the distance between 2 masses increases if both have the same vi but if one was released earlier than the other one. This makes sense to me. However, another version of this question (Q49 in the next section) says the opposite. The boook's answer explanation says that if both skiers are separated by a distance and they have same vi, then the distance will remain the same. But this doesn't make sense because it is as if one started earlier than the other as Q11. They have the same acceleration (gsinO) which makes the earlier skier have more velocity than the later skier, which increases the distance between them. Does anyone know why the book says that if they have same vi, distance between them is same? Thanks in advance! 🙂

 

[TieuBachHo]

I don't have the book so my answer is only relative. It is not the same thing as if one starts earlier than the other. When the first one has a head start, it already has a momentum or initial velocity gained by acceleration (in this case). The distance will continue to separate as they progress. However, when both skiers are separated but start at the same time with same Vi, it's a diff. scenario. Either skier doesn't have that gained initial velocity due to acc., so the distance between them reamains the same. (As long as the angle doesn't change and no external stimulus, the acceleration is constant for conservative forces <== this crap just mean that you don't have to worry about their acc.)

Now if you still don't get this, then you can try to work out a few prob. and see what's diff. about them.