Question

A ball is dropped gently from a height of 20m. If it’s velocity increases uniformly at the rate of 10metre per second square, then the velocity with which it reaches the ground and time taken to reach the ground respectively are

Answer 1

as it is dropped from a height:

u=0m/s

h=s=20m

a=10m/s^2

according to the question,

s=ut+1/2at^2

20=0(t)+1/2(10)t^2

20=0+1/2(10)t^2

20=5(t)^2

t^2=4

t=2seconds

according to third equation of motion

v=u+at

v=0+10×2

v=20m/s