MOMENTUM

2 marks · Easy

(a)

A small skateboard of mass 2 kg is at rest. A person jumps onto it, giving the skateboard a velocity of 3 m/s. Calculate the momentum of the skateboard after the jump.

[1 mark]

(b)

If the person and skateboard have a combined mass of 40 kg and move off together at 2 m/s after the jump, what is their total momentum?

[1 mark]

Work this out on paper, then compare with the answer and worked solution below. With a free account you can submit written answers for marking.

Show answer

(a) 6 kg m/s

(b) 80 kg m/s

Common mistakes: Incorrect mass used; Incorrect velocity

Show mark scheme and worked solution

Marking points

A1 (a) · 1 mark · Correct calculation of momentum for the skateboard.

A1 (b) · 1 mark · Correct calculation of total momentum for combined mass.

Worked solution

a) Momentum = mass × velocity = 2 kg × 3 m/s = 6 kg m/s.

b) Momentum = combined mass × velocity = 40 kg × 2 m/s = 80 kg m/s.