Answer:
<h2>The angular velocity just after collision is given as</h2><h2>

</h2><h2>At the time of collision the hinge point will exert net external force on it so linear momentum is not conserved</h2>
Explanation:
As per given figure we know that there is no external torque about hinge point on the system of given mass
So here we will have

now we can say

so we will have


Linear momentum of the system is not conserved because at the time of collision the hinge point will exert net external force on the system of mass
So we can use angular momentum conservation about the hinge point
Answer:
b
Explanation:
I think im not really sure tho
were solving for v velocity of the ball after it has hit the bottle. a. momentum ->p=mv->ball + bottle momentum during hit = ball + bottle momentum after hit-> ball (.5*21)+ bottle (.2*0) (it's 0 because the the bottle is standing still) = ball after hit (.5*v)+bottle after hit (.2*30) -> 10.5+0=.5v+6 ->4.5=.5v->v=9m/s
b. if bottle was heavier the ball would be slower so final velocity would decrease