A ball is projected horizontally from the top of a hill with a velocity of 20m/s. If it reaches the ground 4 seconds later, what is the height of the hill? (g = 10m/s²)

A. 20m
B. 40m
C. 80m
D. 160m
E. 200m

Correct Answer:

Option C – 80m

Explanation

Initial horizontal velocity = 20m/s

Initial vertical velocity = 0

s = ut + ½gt² = 0 x 5 x 4²

= 80m