Contents
Independent final check
Explain without the key
deduce / give / state / calculate / explain
Final check
A hovercraft moves over flat, wet sand. A tracker on it records its velocity every 2.0 s in four runs, P to S. The table shows the results. (a) Deduce the resultant force on the hovercraft in run P. (b) Give the direction of the resultant force in run Q and in run R. (c) In run S, state what the resultant force changes, and give its direction at the start of the run. (d) In run Q, three horizontal forces act on the hovercraft: the push of its fan, 900 N towards the east; air resistance, 150 N towards the west; and the pull of a rope towing a small boat, towards the west. The resultant force is 400 N towards the east. Calculate the pull of the rope. (e) A pupil says: “In run R, at 4.0 s the hovercraft is not moving, so the resultant force on it at that moment is zero.” Explain why this is wrong.
deduce: reach a conclusion from the information given. give: produce an answer from the information or from memory. state: give a concise answer. calculate: work out the answer from the data. explain: give reasons and connect them to evidence.
| Run | Velocity at 0 s | at 2.0 s | at 4.0 s | at 6.0 s |
|---|---|---|---|---|
| P | 5.0 m/s east | 5.0 m/s east | 5.0 m/s east | 5.0 m/s east |
| Q | 2.0 m/s east | 4.0 m/s east | 6.0 m/s east | 8.0 m/s east |
| R | 6.0 m/s east | 3.0 m/s east | 0 | 3.0 m/s west |
| S | 5.0 m/s east | 5.0 m/s north-east | 5.0 m/s north | 5.0 m/s north-west |
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Scope and sources
Cambridge IGCSE Physics 0625 · 2026–2028 v2 · Original learning materials.
Scalars have size only and vectors have size and direction (1.1.4); distance, speed, time, mass, energy and temperature are scalars (1.1.5); force, weight, velocity, acceleration, momentum, electric field strength and gravitational field strength are vectors (1.1.6); the resultant of two vectors at right angles, by scale drawing and by calculation, for forces and velocities only (1.1.7); the resultant of two or more forces along the same straight line (1.5.1.3); with no resultant force an object stays at rest or moves in a straight line at constant speed (1.5.1.4); a resultant force changes the velocity of an object by changing its speed or its direction of motion (1.5.1.5); F = ma, with the force and the acceleration in the same direction (1.5.1.11); motion in a circular path due to a force at right angles to the motion: with the mass and the radius constant, a bigger force goes with a bigger speed; with the mass and the speed constant, a bigger force goes with a smaller radius; with the speed and the radius constant, a bigger mass needs a bigger force (1.5.1.12). 1.1.4–7, 1.5.1.11 and 1.5.1.12 are Supplement. F = mv²/r is not required and is not used. Springs are in Stretching springs, friction and drag in Acceleration, falling and drag, moments in Moments and balance, and momentum in Momentum and collisions.
Apparatus, amounts and times in the experiment are illustrative. Real practical work follows a teacher-approved safety method.
Official Cambridge syllabus