A rock is thrown upward with a velocity of 15 meters per second from the top of a 30 meter high cliff, and it misses the cliff on the way back down. When will the rock be 10 meters from the water, below? Round your answer to two decimal places.

Question

A rock is thrown upward with a velocity of 15 meters per second from the top of a 30 meter high cliff, and it misses the cliff on the way back down.  When will the rock be 10 meters from the water, below?  Round your answer to two decimal places.

I am not understanding how to start this

Hannah · Accepted Answer

4.07 seconds

Steve · Answer

Better review your motion equation. h = Ho + Vo*t - 1/2 gt^2 the height above the water, using g = 10, is thus h = 30 + 15t - 5t^2 So, just solve for t when h=10

Anonymous · Answer

A rock is thrown upward with a velocity of 15 meters per second from the top of a 34 meter high cliff, and it misses the cliff on the way back down. When will the rock be 4 meters from ground level? Round your answer to two decimal places.