Question

a ball of mass 100g moving with a velocity of 30m/s is stopped by a boy in 0.05 sec.calculate the force applied by the boy to stop the ball .

Answer 1

m=100g=0.1kg
u (initial velocity) =30m/s
v (final velocity) =0
t =0.05sec

using the equation,
v=u+gt
=>0=30+g x 0.05
=>0=30+0.05g
=>0-30=0.05g
=>-30=0.05g
=>-30/0.05= g.(here -ve sign means
retardation)
So,
g=600 m/s^-2


Now, let the force applied be F
=>F=m x g = 0.1 x 600 = 60 N

Here's ur solution

Answer 2

acceleration =v/t

=30m/0.05sec =600m/sec

force = mass . acceleration

         =100.600=60000 newton