Question

The height of the empire state building is 318 m if a stone is dropped from the top of the building what is the stones velocity just before it strikes the ground

Answer 1

79 m/s. A stone dropped from the top of the Empire State Building will have a velocity of 79 m/s just before it strikes the ground.

This problem is about free fall, to find the velocity of the stone before it strikes the ground we have to use the equation $v_{f}^{2}=v_{0}^{2}+2gh$, the initial velocity  of the stone is 0 m/s. Then:

$v_{f}^{2}=2gh$

$v_{f}=\sqrt{ 2gh}$

Solving the equation above with g = 9.8 m/s², and h = 318.0 m:

$v_{f}=\sqrt{ 2(9.8m/s^{2})(318.0m)}= 78.95 m/s$

$v_{f}$≅ 79 m/s