Question

A bullet penetrates a 20cm thick wall its initial and final velocities are 200ms and 120 ms

Answer 1

Answer:

penetrated by bullet (S) or displacement of bullet in presence of resistive force = 10 cm = 0.1m. ... A gun of mass 5 kg fires a 50 gram bullet with a velocity of 200 m per second

Answer 2

Let the mass of the bullet be m. The initial kinetic energy of the bullet= ½mv².

KE=½×m×20×20=200m.

This much energy is spent in penetrating the wall upto 5cm. Let the force be F.

Work done =Force×displacement.

W=F×5×10-².

So, 200m= ma×0.05 (F=ma)

Therefore answer= a= 4000 ms-².