Question

a falling rock undergoes a change of velocity 112m/s due to an acceleration of 9.8 m/s2, how long did it fall?

Answer 1

a= v-u/t
Change in velocity = v-u = 112
a = 9.8

t=(v-u)/a =112/9.8
t= 11.42s

Answer 2

Considering the initial velocity is 0m/s, falling from rest

vi = 0m/s

vf = 112m/s

a = 9.8m/s^2

t = ?

a = (vf - vi)/t

9.8m/s^2 = (112m/s - 0m/s)/t

multiplying both sides with t (time)

--> (9.8m/s^2)t = 112m/s

dividing both sides with 9.8m/s^2

--> t = 11.4s

it took 11.4s for the fall