题目内容
如右图所示,半径为R的圆板匀速转动,B为圆板边缘上的一点,当半径OB转动到某一方向时,在圆板中心正上方高h处以平行于OB方向水平抛出一小球,要使小球刚好能落在圆板上的B点(此后球不反弹),求:
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/201408241333246654003.png)
(1)小球的初速度的大小;
(2)圆板转动的角速度.
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/201408241333246654003.png)
(1)小球的初速度的大小;
(2)圆板转动的角速度.
(1)R
(2)πn
(n=1,2,3……)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824133324712571.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824133324743593.png)
(1) (5分)小球平抛运动的水平位移
R=v0t①小球的竖直位移h=
gt2②由②得t=
代入①得
v0=
=
=R
.
(2) (4分)设小球在运动时间内,圆板转了n圈,其角速度为
ω=
=
=πn
(n=1,2,3……)
(注意:该题中要注意圆周运动的周期性)
R=v0t①小球的竖直位移h=
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824133324774338.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824133324805587.png)
v0=
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824133324852395.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824133324883705.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824133324914552.png)
(2) (4分)设小球在运动时间内,圆板转了n圈,其角速度为
ω=
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824133324946558.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824133325008781.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824133324743593.png)
(注意:该题中要注意圆周运动的周期性)
![](http://thumb2018.1010pic.com/images/loading.gif)
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