Question

如图所示，长木板固定于水平实验台上。放置在长木板处的小球(大小不计)，在水平恒力的作用下向右运动，运动到长木板边缘处撤去水平恒力，小球水平抛出后恰好落在光滑斜面顶端处，且速度方向平行于斜面。己知小球质量为，与水平长木板间的动摩擦因数为，长木板长为，距离水平地面的高度为，斜面倾角为、、两点间竖直高度为。求：
(1)的水平距离；
(2)水平恒力的大小；
(3)小球落地时速度的小。

Answer 1

（1）
（2）
（3）

（1）小球落在处时，············································· 2分
·································································· 2分
小球从到
···················································································· 2分
··················································· 2分
（2）小球从到 
由动能定理得；
·········································································· 3分
······································································ 2分
（3）小球从到地，机械能守恒得：
······································································· 3分
······································································ 2分
（其他正确解法同样得分）