A girl at the bottom of a 100m high cliff throws a tennis ba

A girl at the bottom of a 100m high cliff throws a tennis ball vertically upwards.A boy at the very top of the cliff drops a golf ball so that it hits the tennis ball while both ball are still in the air.
Q1:With what speed is the tennis ball thrown so that the golf ball strikes it at the top of its path?
Q2:What's the position of the tennis ball when the golf ball strikes it? 小茶杯小茶盖 1年前他留下的回答 已收到2个回答

蓝色海瑙 网友

该名网友总共回答了12个问题，此问答他的回答如下：采纳率：100%

Solution:
Define t1 as the time at which two balls meet each other,the distance the tennis has fallen when two balls meet as S1,the distance the golf ball rises as S2,the initail velocity of tennis ball as v0
since the point two balls meet are the top point of golf ball 's path
so that t1=v0/g
then
S1=1/2*g*t1^2
S2= v0*t1-1/2*g*t1^2
get s1=s2=50m
assume g=10m/s^2
t1=10^0.5 s which is about 3.162s
v0=g*t1=31.6m/s
Answer:Q1 With the speed of 31.6m/s the tennis ball is thrown so that the golf ball strikes it at the top of its path
Q2:The meet at the middle point of the cliff which is 50m from both the top and the bottom.
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If any question,let me know.

1年前他留下的回答

5

lxzhr 网友

该名网友总共回答了39个问题，此问答他的回答如下：

前提是高尔夫球为静止下落，且与网球一同抛出。
v*t=100 （m）
v/g=t
推出v≈31.3m/s
与高尔夫球相撞时网球竖直方向上的速度可能向上，0，向下- - 关于位子可以画一下小球的h-t图像。其中高尔夫球的图像是固定的，网球的图像随着初始速度的改变是一系列相似的抛物线。求它们的交点在h轴上的取值就行。...

1年前他留下的回答

2

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