ANSWER Below with question

1) A hockey ball of mass 200 g travelling at 10 m s-1 is struck by a hockey STICK so as to return it along its original path with a velocity at 5 m s-1. Calculate the change of momentum occurred in the motion of the hockey ball by the force applied by the hockey stick

Answer

HELLO DEAR,

GIVEN:-

Mass of ball (m) = 200 g = 0.2 kg

Initial velocity of ball () = 10 m

Initial momentum of ball = = 0.2 kg x 10 m = 2 N s

Final velocity of ball = - 5 m (Minus sign denotes that ball is moving in opposite direction.)

Final momentum of ball = = 0.2 kg x -5 m = -1 N s

Change in momentum = Final momentum - Initial momentum = - 1Ns - 2Ns = - 3N s. (Minus sign denotes change in momentum in the direction opposite to the direction of initial momentum of the ball.

2) A bullet of mass 10 g travelling horizontally with a velocity of 150 ms

−1

strikes a stationary wooden block and comes to rest in 0.03 s. Calculate the distance of penetration of the bullet into the block. ALSO calculate the magnitude of the force exerted by the wooden block on the bullet.

ANSWER

Initial velocity of the bullet, u=150 ms

−1

Final velocity of the bullet, v=0

Mass of the bullet, m=10 g=0.01 kg

Time taken by the bullet to come to rest, t=0.03 s

Let distance of penetration be s

v=u+at

0=150+a(0.03)

⟹a=−5000 ms

−2

(- sign shows retardation)

v

2

=u

2

+2as

0=150

2

+2×(−5000)×s

s=2.25 m

Magnitude of the force exerted by the wooden block, ∣F∣=m∣a∣

∣F∣=0.01×5000=50 N