Question

How much work is needed to be done on a ball of mass 50g to give it a momentum of 5kgms^-1 ?

Answer 1

Given :

initial velocity ( u ) = 0 m/s

final velocity ( v ) = ?

mass ( m ) = 50 g

                 = 50 / 1000 kg

                 = 0.05 kg

Momentum ( p ) = 5 kg m/s

Formula :

Momentum = mass × velocity

Calculate the final velocity :

5 kg m/s = 0.05 kg × v

= > v = 5 kg m/s / ( 0.05 kg )

= > v = 100 m/s

Formula :

Work = change in kinetic energy

          = 1/2 m v² - 1/2 m u²

1/2 m u² = 0 because u = 0

Hence work = 1/2 m v²

Find the work

W = 1/2 m v²

= > W = 1/2 × 0.05 × (100)²

= > W = 1/2 × 0.05 × 100 × 100

= > W = 1/2 × 5 × 100

= > W = 5 × 50

= > W = 250 J

ANSWER :

The work done is 250 J

Answer 2

Answer:

250 J

Explanation:

m = 50 g

=> m = 0.05 kg

p = mv

=> v = p / m

=> v = 5 / 0.05

=> v = 100 m/s

W = $\frac{1}{2}$ $mv^{2}$ - $\frac{1}{2}$ $mu^{2}$

=> W = $\frac{1}{2}$ $mv^{2}$ - 0

=> W = $\frac{1}{2}$ $mv^{2}$

=> W = $\frac{1}{2}$ * 0.05 * $100^{2}$

=> W = $\frac{500}{2}$

=> W = 250 J

HOPE IT HELPS!!

:)