Question

a ball of mass 400g is moving to the right with a speed of 12.4 m/s. it hits a wall and bounces back to the left with a speed of 8.9m/s .what was the magnitude of change is momentum of the ball , in units of kg.m/s?

Answer 1

Let us assume,

M is the mass of the ball.

V is the speed of the ball moving right side.

U is the speed of the ball bounced back to left side.

So, M=400g

Conversion of grams to kg:

1000g = 1kg Then

400g = M i.e M*1000g=1kg*400g

M=1kg*400g/1000g

M=4kg/10

M=0.4kg

So finally M=0.4kg

V=12.4 m/s.

U=8.9 m/s.

Now,

Magnitude of change in momentum of the ball = M*(V-U)

= 0.4kg*(12.4-8.9)m/s

=0.4Kg*3.5m/s

=1.4 Kg.m/s

Magnitude=1.4Kg.m/s