A penny is dropped from the top a 50-meter-tall building. How long does it take for the penny to reach the ground?

Question

I have tried to solve this problem by myself but I end up with a different answer or It's not the correct one, any help here?

Answer 1

If there is no air resistance, use

h = gt² / 2 ⇒

t = √(2h/g)

h = 50 m

g = 9.8 m/s²

Plug in the numbers and get t in seconds.