Question

momentum of bullet of mass 20g fired from a gun is at 8kgm/s. Calculate the kinetic energy of a bullet in kJ

Answer 1

Use the formula

E= p^2/2m where,

E denotes kinetic energy

p denotes momentum and

m is the mass of the bullet.

Answer 2

Momentum (p)=8 =mv (mass×velocity)

Kinetic energy = 1/2 mv^2

So v need to find velocity as we already have the mass that is 20g or 0.02kg

v= 8/0.02

= 400m/s

And we use the kinetic energy formula

1/2mv^2 =1/2×0.02×(400)^2

=1600J

=0.16KJ

We can alternnatively use the formula

Kinetic energy= (momentum)^2/2m