Question

A bullet of mass 20g strikes a target with a velocity 100m/s and comes to rest. 50% kinetic energy of the bullet raises its temperature by 25
c. Calculate its internal energy

Answer 1

internal energy of the bullet after striking a target = 50 j .

Explanation:

initial velocity = 100 m/s

final velocity = 0 m/s

change in kinetic energy ΔKE = 1/2 m ( V² final - V² initial)

    ΔKE = 0.5* 0.02* (0 - 100*100  )

            = -100 j

.

50 % of KE  = 100 *( 50 / 100 )

                   = -50 j

negative means KE is lost and loss in kinetic energy is stored as the internal energy

so internal energy = 50 j .