Question

A ball of mass 100g is moving with a velocity 10m/s is stopped by a boy in 0.2 seconds. Calculate the force applied by the boy to stop the ball.

Answer 1

mass of ball =100g , velocity of ball= 10m/s ,ball stop by boy in 0.2 sec.then force=mass×acceleration but acceleration is not given,acceleration=initial velocity - final velocity/time ,but initial velocity= 10m/s and final velocity=0m/s and time = 0.2 second. therefore,acceleration =10-0/0.2=50,therefore,force=m×a=100×50=500 Newton

Answer 2

Initial velocity, u= 10m/s

Final velocity, v= 0m/s

Time=0.2 seconds

Acceleration= ?

( as we know that to find acceleration the formula is v-u/ time taken

Acceleration= 0-10/0.2= -50m/s^2

Mass= 100g

( converting into kilograms )

100/1000= 0.1 kg

Then ,

Force = mass×acceleration

F=m×a

= 0.1× -50

= -5 Newton