Answer:
3.0 kg
Step-by-step 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
