Question

A 1200 kg wrecking ball is moving at 2.50 m s' north towards a 1500 kg
wrecking ball moving at 4.00 ms south. Calculate the final velocity of the
1500 kg ball If the 1200 kg ball rebounds at 3.50 m s south.
Urgent pls

Answer 1

Given :-

◉ Ball A of mass m = 1200 Kg is moving with velocity v = 2.50 m/s towards Ball B of mass M = 1500 Kg which is also moving towards Ball A with velocity V = -4 m/s (because Ball B is moving in Opposite direction).

◉ After collision, Ball A moves with velocity v₁ = -3.50 m/s (because It is moving in opposite direction)

To Find :-

◉ Final velocity of Ball B after collision.

Solution :-

We know, Conservation of a system remains the same at every instant. Hence, The momentum of Ball A + Ball B would be equal to the momentum of Ball A + Ball B after collision.

So, We have, before collision

⇒ Momentum of Ball A + Momentum of Ball B

⇒ mv + MV

⇒ 1200×2.50 + (1500 × -4)

⇒ 3000 - 6000

⇒ -3000 kg.m/s ...(1)

Similarly, After the collision

⇒ Momentum of Ball A + Momentum of Ball B

⇒ mv₁ + MV₁

⇒ 1200×-3.50 + 1500V₁

⇒ 1500V₁ - 4200 kg.m/s ...(2)

(1) = (2) [Law of conservation of momentum]

⇒ -3000 = 1500V₁ - 4200

⇒ 1500V₁ = 1200

⇒ V₁ = 12/15

⇒ V₁ = 0.8 m/s

Hence, The velocity of the Ball B after collision will be 0.8 m/s towards the North direction.