Answer:
8.3
Explanation:
thats what i think sorry if its wrong im ok at doing this stuff
Answer:

Explanation:
Given that:
mass of object A, 
mass of object B, 
speed of object A, 
So, according to the conservation of momentum, the momentum before collision is equal to the momentum after conservation.




Answer:
Explanation:
Initially the two boys were sitting on the periphery , total moment of inertia
= 1/2 M r² + 2mr² ; M is mass of the merry go round , m is mass of each boy and r is the radius
1/2 x 200 x 2² + 2 x 40 x 2²
= 400 + 320
I₁ = 720 kg m²
Finally the two boys were sitting at the middle , total moment of inertia
= 1/2 M r² + 2m( r/2)² ; M is mass of the merry go round , m is mass of each boy and r is the radius
1/2 x 200 x 2² + 2 x 40 x 1²
= 400 + 80
I₂ = 480
Now the system will obey law of coservation of angular momentum because no torque is acting on the system.
I₁ω₁ = I₂ω₂ , I₁ and ω₁ are moment of inertia and angular velocity of first case and I₂ and ω₂ are of second case.
720 X 12 = 480 ω₂
ω₂ = 18 rad / s