Question

急急急~~~麻烦解决一个物理问题。。英文的！！！

A skier starts from rest at the top of a hill. The skier coasts down the hill and up a
second hill, as the drawing illustrates. The crest of the second hill is circular, with a
radius of r=36 m. Neglect friction and air resistance. What must be the height h of
the rst hill so that the skier just loses contact with the snow at the crest of the second
hill?(Hint: Here you may want to use both energy conservation and force methods as
part of your solution. In any case you should identify what forces would be directed
radially inwards when the skier is at the crest of the second hill and remember that
these are the forces that would generate the skier's centripetal acceleration. Of these forces, which would vanish if contact between the skier and the hill was lost? This force might then be set to zero in the solution.)

Answer 1

一位滑雪者开始静止在山顶上。海岸滑雪者,下了山
第二,说明图纸上。第二的顶是循环,山
半径的r = 36米。忽视摩擦和空气的阻力。我们必须高度h的
皇家,山滑雪只是失去与雪的顶第二
希尔吗?(提示:在这里你可以想同时使用方法节约能源和力量
你的解决方案的一部分。在任何情况下你应该确定什么力量会指导
当滑雪者内非在第二的顶山,记住这一点
这些力量会导致滑雪者的向心加速度。这些力量,这就会消失如果接触、还有小山滑雪者丢失的?这种力量也许到那时就会被设置为零的解决办法。)
我不几道答案

Answer 2

题目大意：滑雪者从第一个坡滑下，到第二个小坡的顶部的时候，人刚好离开雪面(即速度与小坡所在的圆相切)，求第一个小坡的比第二个小坡高出h是多少？
设人在第二个小坡顶部的速度为v,
由机械能守恒有 mgh=1/2*mv²
当人在第二个小坡的顶部的时候，重力充当向心力
满足mv²/R=mg
联立两式可解得h=18m
所以第一个小坡要比第二个小坡高18米