本题目来源于试卷: gc physics textbook chapter 6 problems，类别为 IB物理学
[问答题]
A child on a sled (total mass m) starts from re);egx8yksc1 nst at9 f6yw/ 6mxg+e/wgy lsjuh7reaa--a0 the top of a hill of height h and slides down. Does the velocity ag66/0e w fw-lxj ys ahamu9+yr/g7e-a t the bottom depend on the angle of the hill if (a) it is icy and there is no friction, and (b) there is friction (deep snow)?
参考答案: (a) If there is no friction to dissipate any of the energy, then the gravitational PE that the child has at the top of the hill all turns into kinetic energy at the bottom of the hill. The same kinetic energy will be present regardless of the slope – the final speed is completely determined by the height. The time it takes to reach the bottom of the hill will be longer for a smaller slope. (b) If there is friction, then the longer the path is, the more work that friction will do, and so the slower the speed will be at the bottom. So for a steep hill, the sled will have a greater speed at the bottom than for a shallow hill.
本题详细解析:
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