FORCE, MASS AND ACCELERATION
3 marks · NormalA car of mass 1,000 kg experiences a forward driving force of 4,000 N and a frictional force of 1,200 N in the opposite direction. Calculate the acceleration of the car. Show all your working.
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Show answer
2.8 m/s^2 (±0.05)
Must show: Calculates resultant force, Substitutes m and F, Final answer with unit
Also accept: Final answer rounded to 3 significant figures
Common mistakes: Forgetting to subtract friction; Wrong units
Show mark scheme and worked solution
Marking points
M1 · 1 mark · Determines resultant force: 4,000 N - 1,200 N = 2,800 N.
M2 · 1 mark · Substitutes mass and resultant force into F = m × a or equivalent. (follow-through)
A1 · 1 mark · Obtains final answer 2.8 m/s^2 with correct unit. (follow-through)
Worked solution
1. Find resultant (unbalanced) force: 4,000 N (forward) - 1,200 N (friction) = 2,800 N (forward).