Units (Energy)

3 marks · Normal

A cyclist moves at a speed of 8 m/s. The total mass of the cyclist and bicycle is 75 kg.

(a)

State the correct SI units for:

(i)

mass

[1 mark]

(ii)

speed

[1 mark]

(b)

Calculate the kinetic energy of the cyclist and bicycle. Give your answer in standard SI units.

[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.

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(a(i)) kg

(a(ii)) m/s

(b) 2400 J

Also accept: 4800 J

Common mistakes: Formula errors (using v instead of v^2); Unit errors

Show mark scheme and worked solution

Marking points

B1 (a(i)) · 1 mark · Correct SI unit for mass: kg

B1 (a(ii)) · 1 mark · Correct SI unit for speed: m/s

M1 (b) · 1 mark · Substitutes values into kinetic energy equation correctly: KE = 0.5 × 75 × (8)^2

A1 (b) · 0 marks · Correct evaluation: 2400 J

Worked solution

a) i) kg ii) m/s

b) Kinetic energy = J