Question

A particle of mass 10 kg moving eastwards with a speed 5 m s⁻¹ collides with another particle of same mass moving northwards with the same speed. The two particles coalesce on collision. The new particle of mass 20 kg will move in the north-east direction with velocity:

• A. 10 m s⁻¹
• B. 5 m s⁻¹
• C. 5√(2) m s⁻¹
• D. none of these

Hint:

Use conservation of momentum in perpendicular directions separately.

Answer 1

The Correct Option is C

Step 1: Momentum in east direction, pₓ = 10 × 5 = 50
Step 2: Momentum in north direction, py = 10 × 5 = 50
Step 3: Resultant momentum, p = √(50² + 50²) = 50√(2)
Step 4: Velocity of combined mass, v = 50√(2)20 = 5√(2)