Question

A 10 g penny is dropped from a building that is 125m high. The penny is initially at rest. Approximately how many seconds does it take the penny to hit the ground?
A)3.2 B) 4.5 C) 10 D) 15 E) 20

Answer 1

Assuming no drag you can simply use:\[d=\frac{1}{2}gt^2\]\[125m=\frac{1}{2}(9.8m/s^2)t^2\]\[t=\sqrt{\frac{(2)(125m)}{9.8m/s^2}}\]