A ball is projected horizontally from the top of a hill with a velocity of 20m-1. If it reaches the ground 4 seconds later, what is the height of the hill? (g = 10ms-2)
A
20m
B
40m
C
80m
D
160m
E
200m
Verified Correct Answer: C.
Physical Principles & Numerical Solution
Initial horizontal velocity = 20ms-1
Initial vertical velocity = 0
s = ut + \(\frac{1}{2}gt^2\) = 0 x 5 x 42
= 80m
Source: Myschool Past Questions Archive (Record #33193)