Question

A car with a gun mounted on it is kept on
horizontal friction less surface. Total mass of car, gun and shell
is 50 kg. Mass of each shell is 1 kg. if shell is fired horizontally with relative velocity 100 m/sec
with respect to gun, what is the recoil speed of car after second shot in nearest integer?[15 JP 1108941​

Answer 1

Answer: Center of mass of velocity of shell = 0 (initially at rest)

Therefore , 0 = 49 m x V + m x 200

V = -200/49 m/s

200/49 m/s towards left .

Another shell is fire , then the velocity of the car , with respect to platform is

V' = 200/49 m/s towards left

Another shell is fired , then the velocity of the car with respect to platform is

v' = 200/48 m/s towards left

Now , the velocity of the car with respect to earth is (200/49 + 200/48) = 19400/2352 = 8.24 m/s towards left.