Question

Two billiard ball A and B each of mass `50g ` and moving in opposite direction with speed of `5ms^(-1)` each, collide and rebound with the same speed. The impulse imparted to each ball is
A. `0.25"kgms"^(-1)`
B. `0.5"kgms"^(-1)`
C. `0.8"kgms"^(-1)`
D. `0.125"kgms"^(-1)`

Answer 1

Correct Answer - B

Initial momentum of ball A=(0.05kg)(5ms^(-1))=0.25`kg ms^(-1)`
As the speed is reversed on collision,
Final momemtum of the ball `A= (0.05 kg) (-5ms^(-1))=-0.25kg ms^(-1)`
Impulse imparted to the ball A
=Change in mometnym of ball A
=Final momentum-Initial momentum
`=-0.25 "kg ms"^(-1)-0.25"kg ms"^(-1)=-0.5"kg ms"^(-1)`
Similarly,
Initial momentum of ball `b=(0.05kg)(-5ms^(-1))=-0.25 kgms^(-1)`
Final momentym of ball `B=(0.05 kg)(5ms^(-1))==+0.25kgms^(-1)`
Impulse imparted to ball B=`(0.25kg ms^(-1))-(-0.25 kg ms^(-1))` =`0.5kgms^(-1)`
Impulse imparted to each ball is `0.5kgms^(-1)` in magnitude. THe two impulses are opposite in direction.