MOMENTUM
3 marks · NormalA cyclist and their bicycle have a combined mass of 90 kg. If their velocity changes from 6 m/s to 0 m/s in 2 seconds, calculate the average resultant force acting on them while stopping.
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-270 N (±2)
Also accept: 270 N, direction stated as 'opposite direction of motion'
Common mistakes: Missing negative sign
Show mark scheme and worked solution
Marking points
M1 · 1 mark · States or uses the correct equation F = (mv - mu)/t with correct values.
A1 · 1 mark · Performs subtraction (0 - 540).
A2 · 1 mark · Final answer of -270 N with unit.
Worked solution
Initial momentum, mu = 90 × 6 = 540 kg m/s
Final momentum, mv = 90 × 0 = 0 kg m/s