Question

如圖所示，長木板固定于水平實驗臺上。放置在長木板處的小球(大小不計)，在水平恒力的作用下向右運動，運動到長木板邊緣處撤去水平恒力，小球水平拋出后恰好落在光滑斜面頂端處，且速度方向平行于斜面。己知小球質(zhì)量為，與水平長木板間的動摩擦因數(shù)為，長木板長為，距離水平地面的高度為，斜面傾角為、、兩點間豎直高度為。求：
(1)的水平距離；
(2)水平恒力的大小；
(3)小球落地時速度的小。

Answer 1

（1）
（2）
（3）

（1）小球落在處時，············································· 2分
·································································· 2分
小球從到
···················································································· 2分
··················································· 2分
（2）小球從到 
由動能定理得；
·········································································· 3分
······································································ 2分
（3）小球從到地，機械能守恒得：
······································································· 3分
······································································ 2分
（其他正確解法同樣得分）