A 2kg toy car traveling at 2m/s strikes a second toy car at rest. The mass of the second toy car is 3. The two stock together and move off together. What is their resultant speed?

Mass of first car = Initial mass (Mi) = 2 kg

Initial velocity (Vi) = 2 m/s

Mass of both cars together = Final mass (Mf) = 2 + 3 kg = 5 kg

Final Velocity (Vf) = ?

Applying law of conservation of momentum,

Mi x Vi = Mf x Vf

2 x 2 = 5 x Vf

Vf = 4/5 = 0.8 m/s