S1 Science: Forces, Motion And Simple Machines (Paper 4 (error Clinic))

S1 Science: Forces, Motion and Simple Machines (Paper 4 (error clinic))

2026-11-14

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Tutor Prep Guide · Speed and acceleration calculations, Newton laws and friction, lever moments, mechanical advantage of pulleys and inclines, plus efficiency and stopping distance

S1 Science: Forces, Motion and Simple Machines (Paper 4 (error clinic))

This paper reworks the commonest wrong answers, including the units of mass and weight, inertia, the direction of friction, moments and mechanical advantage.

Direct answers　Each error should be named as a faulty concept, a reversed direction or a unit mistake.

01　Paper details (check answers afterwards)

Item	Detail
Questions	10
Suggested time	20
Difficulty mix	Foundation 3 · Intermediate 3 · Challenge 3 · Error redo 1
Chapter	Chapter: S1 Science: Forces, Motion and Simple Machines
Level	S1

02　Questions (10 items)

FoundationWhat is the unit of mass?
FoundationWhat determines the size of inertia?
FoundationWhich way does friction act on a sliding object?
IntermediateHow is average speed calculated?
IntermediateHow is a moment calculated?
IntermediateHow much force does an ideal movable pulley save?
ChallengeAn incline saves force but lengthens the path, so how much work does an ideal incline do?
ChallengeHow many m/s is 72 km/h?
ChallengeA distance of 150 m takes 30 s. What is the average speed?
Error redoIf an object moves, some push must act on it. Is this right?

03　Answers and one-line notes

#	Answer	One-line note
1	The kilogram, written kg	Mass measures the amount of matter while weight is a force measured in N.
2	Mass	The larger the mass the harder it is to change its motion, so the greater the inertia.
3	Opposite to the direction of motion	Friction always opposes relative sliding, so it points against the motion.
4	Total distance divided by total time	Do not just average the first and last speeds unless the acceleration is uniform.
5	Force times the moment arm	The moment arm is the perpendicular distance from the pivot to the line of action, not to the point of application.
6	Half	The mechanical advantage is 2, but the rope is pulled twice as far.
7	The same work as lifting straight up	The product of force and distance is unchanged, only how it is shared changes.
8	20 m/s	Divide by 3.6, and 72 divided by 3.6 gives 20.
9	5 m/s	150 divided by 30 gives 5.
10	No, with zero resultant force an object keeps moving uniformly in a straight line	Inertia keeps it moving with no resultant force, and only friction brings it to rest.

04　What to do after marking

After marking, redo only the wrong items and write down which step went wrong (formula, unit, or misread number).
Repeat the same item two days later; move to the next paper only when both attempts are correct.
Parents only need the answer and note columns; there is no need to explain every item.

For mechanics questions ask three things: whether the question asks for force, energy or time, whether units are already in m, s and N, and whether equilibrium or constant work is the premise.Tutor Registration →

Questions and answers are written originally by the TutorZone team and are not taken from any school, publisher or examination authority paper. Every value is checked by computer.