At the top of a cliff 100 m high,Raoul throws a rock upward with velocity 15.0 m/s.How much later should he drop a second rock from rest so both rocks arrive simultaneously at the bottom of the cliff?
A)8.08 s
B)3.31 s
C)5.02 s
D)1.78 s
E)0.89 s

Question

At the top of a cliff 100 m high,Raoul throws a rock upward with velocity 15.0 m/s.How much later should he drop a second rock from rest so both rocks arrive simultaneously at the bottom of the cliff?​
A)8.08 s
B)3.31 s
C)5.02 s
D)1.78 s
E)​0.89 s

Quizplus · Accepted Answer

The first rock is thrown upwards and will take time to reach its peak and then fall back down. The total time for the first rock to hit the ground can be calculated using the kinematic equation. The second rock is dropped from rest, so it only falls under gravity. The time difference between the two rocks' release times should be such that they hit the ground simultaneously. Calculating these times shows that the second rock should be dropped 1.78 seconds after the first rock is thrown.

At the Top of a Cliff 100 M High,Raoul Throws