Question

a bullet of mass 0.015kg strikes a metal plate of thicknesses 10cm with a velocity of 400m/s and emerge from it with a velocity of 260 m/s. find the average resistance offered by the plate to the motion of bullet

Answer 1

The average resistance offered is 6930N.

Mass of the bullet = m = 0.015 kg (Given)

Velocity =u = 400 m/s (Given)

Second velocity = v = 260 m/s (Given)

Therefore,

Change in kinetic energy = work done by the resistive force

= 1/2m ( v² − u² ) = F × thickness of plate

= 0.5 × 0.015 ( 160,000 − 67,600 ) = F × 0.1F

= −6930 N

where  the negative sign depicts that the direction of force is opposite in nature.

Thus, the average resistance offered is 6930N.