A 100 kg cannon at rest is loaded with a 10 kg cannonball. When fired horizontally, the cannon ball leaves the cannon with a speed of 90 m/s. What is the recoil speed of the cannon

recoil speed is 9 m/s

Explanation:

given data

cannon mass = 100 kg

cannonball = 10 kg

speed = 90 m/s

solution

we use here the law of conservation of momentum

as total momentum of the cannon and cannonball both before and after the shot will be conserve

and before shot

total momentum p = 0   ..............1

and

After the shot

the total momentum p = mv + MV     .............2

and

momentum is conserved so we can say from both equation

0 = mv + MV

put here value and we get

V =

V =

V = -9 m/s

here V = -9 m/s negative sign show that cannon will move in the opposite direction to the cannonball

so that recoil speed is 9 m/s