FORCE, MASS AND ACCELERATION
3 marks · EasyA child pushes a toy lorry of mass 4.0 kg along a smooth surface. The lorry accelerates at 1.2 m/s².
Calculate the size of the unbalanced force acting on the lorry. Show your working.
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4.8 N (±0.1)
Common mistakes: 4.0 + 1.2; Multiplying by 9.8 instead of acceleration; Wrong units
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Marking points
M1 · 1 mark · States or uses the correct equation F = m × a.
M2 · 1 mark · Substitutes the correct values for m and a.
A1 · 1 mark · Gives the correct answer with correct unit: 4.8 N.
Worked solution
Equation:
Substitute values:
Calculate: