Question

The momentum of a bullet of mass 20 g fired from a gun is 10 kg m/s. What will be the kinetic energy of this bullet in kJ?

Answer 1

Given:

Mass of bullet (m) = 20 g = `20/1000` kg = 0.02 kg

Momentum (p) = 10 kg . m/s

Use the formula relating Kinetic Energy and Momentum:

KE = `p^2/(2m)`

= `10^2/(2 xx 0.02)`

= `100/0.04`

= 2500 J

Convert Joules into kilojoules (KJ):

KE = `2500/1000`

= 2.5 kJ

The kinetic energy of the bullet is 2.5 kJ.