Time of free fall,
s=ut+12at2
initial velocity is 0 so
h=12gt2=1210×0.52=1.25m
(c) height from ground is 1.25m
Apply kinematic equation of motion
v2−u2=2as
v=√2gh=√2×10×1.25=5ms−1
(a)Speed of car striking the ground is 5ms−1
(b)Average speed, vavg=v−0h=51.25=4ms−1