A rock is dropped from a 200 m high cliff. How long does it take to fall (a) the first 100 m and (b) the last 50 m?
The basic equation you want is:
s=at22
Solving for t:
t=2sa−−−√
We’ll assume a=9.8 , so 2a−−√=14.9−−−√≈0.4518
So, for (a)s=100 , so t=0.4518100−−−√=4.518
The total time is 0.4518200−−−√≈6.389
The time to fall 150 m is 0.4518150−−−√≈5.533
So the time to fall the last 50 m is 6.389 - 5.533 = 0.856 seconds
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