3. A projectile is fired from a vertical cliff edge (height = 100 m) with a horizontal velocity of 20

m/s. The projectile hits the ground (height = 0 m) approximately:

A. 180 m from the base of the cliff

B. 90 m from the base of the cliff

C. 7 s after being fired

D. 9 s after being fired

E. 90 s after being fired

Refer to the diagram shown below.

u = 20 m/s, the horiontal launch velocity

v = 0, initial vertical velocity

Assume that wind resistance may be ignored.

The time, t, of the flight is given by

(1/2) * (9.8 m/s²) * t² = (100 m)

t² = 100/4.9 = 20.4082

t = 4.5175 s

Th horizontal distance traveled is

d = (20 m/s) * (4.5175 s) = 90.35 m

Answer: B

The projectile hits the ground at approximately 90 m from the base of the cliff.