Question

A billiard ball of mass 45 g moving
at a speed of 10 m s-strikes
another ball of mass 30 g at rest.
Now both the balls move together.
Find the common velocity.

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Answer 1

your answer is In the Image

Answer 2

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Common velocity is 6 m/s.

Explanation :

We have :

→ Mass of 1st ball (m₁) = 45 g

→ Mass of 2nd ball (m₂) = 30 g

Velocity of 1st ball (u₁) = 10 m/s

→ Velocity of 2nd ball (u₂) = 0 m/s

To find :

→ Common velocity of the balls.

From the question, we have understood that the

1st ball strikes the 2nd ball (initially at rest) and then the two balls move together. So, let their common velocity be v m/s.

On applying "Law of Conservation of Momentum",

we have :

m₁u₁ + m₂u₂ = (m₁ + m₂)v

45 (10) + 30 (0) = (45 + 30) v

→ 450 + 0 = 75v

→ 450 = 75v

→ v = 450/75

⇒ v = 6 m / s