Two objects, each of mass 1.5 kg, are moving in the same straight line but in opposite directions. The velocity of each object is 2.5 ms-1 before the collision during which they stick together. What will be the velocity of the combined object after collision?

Solution

Given

Mass of first object, m₁ = 1.5 kg

Mass of second object, m₂ = 1.5 kg

Velocity of first object before collision, v₁ = 2.5 m/s

The velocity of the second object which is moving in the opposite direction, v₂ = -2.5 m/s

We know that,

Total momentum before collision = Total momentum after collision

m₁v₁ + m₂v₂ = (m₁ + m₂)v

1.5(2.5) + 1.5 (-2.5) = (1.5 + 1.5)v

3.75 – 3.75 = 3v

v = 0

Therefore, the velocity of the combined object after the collision is 0 m/s