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 [tex]v_{f}^{2}=v_{0}^{2}+2gh[/tex], the initial velocity of the stone is 0 m/s. Then:
[tex]v_{f}^{2}=2gh[/tex]
[tex]v_{f}=\sqrt{ 2gh}[/tex]
Solving the equation above with g = 9.8 m/s², and h = 318.0 m:
[tex]v_{f}=\sqrt{ 2(9.8m/s^{2})(318.0m)}= 78.95 m/s[/tex]
[tex]v_{f}[/tex]≅ 79 m/s
