Two spherical balls of 2.0 kg and 3.0 kg masses are moving towards each other with velocities of 6 m/s and 4 m/s respectively. What must be the velocity of the smaller ball after the collision, if the velocity of the bigger ball is 3 m/s?
Correct answer: D. -4.5 m/s
- A. 1.5 m/s
- B. 2.5 m/s
- C. 3.5 m/s
- D. -4.5 m/s
- E. 5.5 m/s
Explanation
Initial velocity of 2kg mass = 6m/s Initial velocity of 3kg mass = -4m/s [-ve sign shows opposite direction] Final velocity of 3kg mass = 3m/s We have to find final velocity of 2kg mass ◈ In any kind of collision, Linear momentum of system is conserved. Momentum is measured as the product of mass and velocity. ➝ Initial P = Final P ➝ m₁u₁ + m₂u₂ = m₁v₁ + m₂v₂ ➝ (2×6) + (3×-4) = (2v₁) + (3×3) ➝ 12 - 12 = 2v₁ + 9 ➝ 2v₁ = -9 ➝ v₁ = -9/2 ➝ v₁ = -4.5 m/s Hence, small ball will move at velocity of -4.5m/s in opposite direction after collision.
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