Question

A 1 kg block is traveling to the right at a speed of 5 m/s. A 2 kg block is traveling to the left at 1 m/s. If the two blocks collide

and stick together, what is their combined speed?

Answer 1

1 m/s

Step-by-step explanation:

According to the law of conservation of momentum:

`m_(1) u_(1) +m_(2) u_(2) =(m_(1) +m_(2) )v`

We take right to be the positive direction (meaning we put minus in front of the velocity of the block which is travelling to the left):

1 kg * 5 m/s - 2 kg * 1 m/s = (1 kg + 2 kg) * v

5 kgm/s - 2 kgm/s = 3kg * v

3 kgm/s = 3 kg * v

v = 1 m/s