Question

The height of the Empire State Building is 318.00 meters. If a stone is dropped from the top of the building, what is the stone's velocity just before it strikes the ground A –1.75 meters/secondB –18 meters/secondC –79 meters/secondD –636 meters/second

Answer 1

We can use 3rd equation of motion to find the velocity of the stone just before it strikes the ground.

Height = S = 318 meters
Acceleration = a= 9.8 m/s²
Initial velocity = u = 0
Final velocity = v = ?

According to the 3rd equation of motion:

2aS = v² - u²

2(9.8)(318)=v²

v²=6232.8

⇒

v = 78.95 m/s

So, the velocity rounded of to nearest integer will be 79 meters per second.

Thus, C option is the correct answer