Question

A stone is dropped from the roof of a tall building. A person measures the speed of the stone to be 49 m/sec when it hits the ground. The height of the building is closest to:

Select one:
a. 24 meters.
b. 49 meters.
c. 122 meters.
d. 245 meters.

Answer 1

v^2 = u^2 + 2gh
since the stone is dropped, the initial speed is 0.

v^2 = 2gh
49^2 = 2 x 9.8 x h
h = 2401 / 19.6 = 122.5 meters

The height of the building is closest to 122 meters.