An apple drops from a tree and hits the ground in 1.5s what is its speed just before it hits the ground?

Vf - Vo = gT

where

Vf = velocity of apple just before hitting the ground

Vo = initial velocity of apple = 0

T = time for apple to hit the ground = 1.5 sec (given)

g = acceleration due to gravity = 9.8 m/sec^2 (constant)

Substituting appropriate values,

Vf - 0 = 9.8 (1.5)

Vf = 14.7 m/sec.