Question

An air track car with a mass of 6 kg and velocity of 4 m/s to the right collides with a 3 kg car moving to the left with a velocity of 2 m/s. After the collision, the 6kg car continues forward with a velocity of 1 m/s. What is the new velocity of the 3 kg car after the collision?

Answer 1

Remember that moment before collision is equal to the moment after collision.

$(m1 \times u1) + (m2 \times u2) = (m1 \times v1) + (m2 \times u2)$

Plugging in our values,

$(6 \times 4) - (3 \times 2) = (6 \times 1) + (3 \times v2) \\ 24 - 6 = 6 \times 3v2 \\ 18 = 18v2 \\ v2 = 1 {ms}^{ - 1}$