Question

Two objects of masses 100 g and 200 g are moving along the same line and direction with velocities of 2 m s⁻¹ and 1 m s⁻¹, respectively. They collide and after the collision, the first object moves at a velocity of 1.67 m s⁻¹. Determine the velocity of the second object.

Answer 1

Mass of one of the objects, m₁ = 100 g = 0.1 kg 

Mass of the other object, m₂ = 200 g = 0.2 kg 

Velocity of m₁ before collision, v₁ = 2 m/s

Velocity of m₂ before collision, v₂ = 1 m/s

Velocity of m₁ after collision, v₃ = 1.67 m/s

Velocity of m₂ after collision = v₄

According to the law of conservation of momentum:-

Total momentum before collision = Total momentum after collision

∴ m₁v₁ + m₂v₂ = m₁v₃ + m₂v₄

(0.1)2 + (0.2)1 = (0.1)1.67 + (0.2)v₄

0.4 = 0.167 + 0.2v₄

∴ v₄ = 1.165 m/s

Hence, the velocity of the second object becomes 1.165 m/s after the collision.