Question

A1.0 kg cart moving right at 5.0 -- on a frictionless track

collides with a second cart moving left at 2.0 m/s.
The 1.0 kg cart has a final speed of 4.0 m/s to the left, and the
second cart has a final speed of 1.0 m/s
to the right.
What is the mass of the second cart?
Consider rightward as the positive direction.

Answer 1

3.0 kg

Explanation:

Momentum before collision = momentum after collision

m₁ u₁ + m₂ u₂ = m₁ v₁ + m₂ v₂

(1.0 kg) (5.0 m/s) + m (-2.0 m/s) = (1.0 kg) (-4.0 m/s) + m (1.0 m/s)

5.0 kg m/s + m (-2.0 m/s) = -4.0 kg m/s + m (1.0 m/s)

9.0 kg m/s = m (3.0 m/s)

m = 3.0 kg