Force as a push or pull. Effects of force. Types: magnetic, gravitational, frictional, elastic spring. Weight due to gravity. Investigating friction and elastic spring force.
frictional forcegravitational forceelastic springmagnetic force
Forces — types, definitions & effects
A force is a push or a pull. You cannot see a force — you only see what it does to an object. Every force below is either a push or a pull.
Gravitational force
A pull towards the centre of the Earth. Acts on all objects. Gives objects their weight. Weight = gravitational force acting on an object.
Frictional force
Acts between two surfaces in contact. Opposes motion between the surfaces. Can be useful (grip) or unhelpful (slows machines). Produces heat and sound.
Elastic spring force
A push or pull exerted by a compressed or stretched spring/elastic. The spring returns to its original shape once the force is removed.
Magnetic force
A push or pull between magnets or between a magnet and a magnetic material. Acts without contact.
Effects of a force (any force can do these):
1.Move a stationary object
2.Speed up a moving object
3.Slow down a moving object
4.Stop a moving object
5.Change the direction of a moving object
6.Change the shape of an object
Syllabus note: The 2023 syllabus lists two things it does not require: the specific terms "air resistance" and "water resistance", and the direction of frictional force for rolling objects such as wheels and balls. The underlying idea — that friction can act on an object moving through air or water — can still be examined; the paper simply describes the scenario without naming the term. None of the questions below use those terms.
Part A — Multiple choice (Booklet A style · 2 marks each)
Question 1 — MCQ (2 marks)
Booklet AEffects of force
A goalkeeper catches a fast-moving football and brings it to a stop. Which effect of force best describes what happens when the goalkeeper catches the ball?
AThe force moves a stationary object.
BThe force changes the direction of a moving object.
CThe force stops a moving object.
DThe force speeds up a moving object.
The ball was moving — the goalkeeper's hands exert a force that brings it to rest. This is "stops a moving object." Option B would be correct if the ball changed direction but was not stopped — e.g. a deflection.
Which statement about gravitational force is correct?
AGravitational force only acts on objects that are falling.
BThe weight of an object is the gravitational force acting on it.
CGravitational force is a push that acts away from the Earth's surface.
DOnly large objects experience gravitational force.
Gravity acts on all objects at all times, not just falling ones — a book sitting on a table has gravitational force acting on it (its weight). Gravity is always a pull towards the Earth's centre, never a push. Weight and gravitational force are the same thing.
Question 3 — MCQ (2 marks)
Booklet AMagnetic force
A bar magnet is held near each of four objects in turn. None of the objects touches the magnet. Which object will be pushed away from the magnet?
AA steel paper clip
BThe north pole of a second bar magnet, held facing the first magnet's north pole
CA copper wire
DA plastic ruler
Only two like poles repel, so B is the only object pushed away. A steel paper clip is a magnetic material, so it is attracted — pulled towards the magnet, not pushed away. Copper and plastic are not magnetic materials, so they feel no magnetic force at all. Notice that none of this needs contact: magnetic force acts across a gap.
Question 4 — MCQ (2 marks)
Booklet AEffects of force · change of shape
An archer pulls the string of a bow backwards, then lets go. The arrow, which was resting on the string, flies forwards. Which two effects of force are shown, in the order they happen?
AA force changes the shape of an object, then a force moves a stationary object.
BA force moves a stationary object, then a force changes the shape of an object.
CA force changes the direction of a moving object, then a force changes the shape of an object.
DA force changes the shape of an object, then a force stops a moving object.
Pulling the string bends the bow and stretches the string — that is a change of shape. Letting go releases the elastic spring force, which pushes the arrow. The arrow was stationary before it was released, so the second effect is moving a stationary object, not changing the direction of one already moving.
A student investigates how the type of surface affects frictional force. She places a wooden block on four different surfaces and measures the force needed to slide it at a steady speed. The results are shown below.
(a) State the conclusion that can be drawn from this experiment. (1 mark)
(b) State two variables that must be kept the same for this to be a fair test. (1 mark)
(c) The student claims that glass is the best surface for a skateboard ramp. Do you agree? Explain your answer, considering both advantages and disadvantages. (2 marks)
(a)The rougher the surface, the greater the frictional force. Smoother surfaces produce less friction.
(b)Any two of: same wooden block (same mass and size) / same speed of sliding / same direction of pulling / same area of block in contact with surface.
(c)Disagree. Although glass produces very little friction (an advantage for speed), it is dangerous for a skateboard ramp because the very low friction means a skateboarder would have almost no grip and could not control their speed or stop safely. A surface with moderate friction — like wood — would be safer and more practical.
Part (c) is an evaluate-and-justify question — the examiner wants you to consider both sides. Saying only "yes, because less friction means faster speed" or only "no, because it's dangerous" earns 1 mark. Both the advantage AND disadvantage are needed for 2 marks.
Question 6 — Structured (4 marks)
Booklet BElastic spring force · predict & explainDistinction level
A student hangs different masses on a spring and measures how much the spring stretches. The table shows her results.
(a) Describe the relationship between the mass hung and the extension of the spring. (1 mark)
(b) Predict the extension when 400 g is hung. Explain your prediction. (1 mark)
(c) The spring is then compressed (pushed down) instead of stretched. What type of force does the spring exert when compressed? State the direction of this force. (1 mark)
(d) When the mass is removed, the spring returns to its original length. What property of the spring does this demonstrate? (1 mark)
(a)As the mass increases, the extension of the spring increases. (Going further: the extension is directly proportional to the mass — doubling the mass doubles the extension.)
(b)8 cm. The pattern shows every 100 g adds 2 cm of extension. 400 g → 4 × 2 = 8 cm.
(c)Elastic spring force — a push force acting upward, pushing outward against whatever is compressing the spring.
(d)This demonstrates the spring's elasticity — it can return to its original shape after the force is removed.
More mass → more extension · Spring force opposes deformation · Elasticity = returns to shape
For (a), "as the mass increases, the extension increases" is the full answer for the mark — the syllabus asks you to investigate the effects of elastic spring force, not to state a proportionality. Still spot the pattern that every 100 g adds the same 2 cm: that is exactly what part (b) needs.
A ball is dropped onto a trampoline. The diagram shows three moments — the ball falling towards the trampoline (A), the ball at its lowest point (B), and the ball travelling upwards again (C).
(a) Name the force that makes the ball fall towards the trampoline at moment A. (1 mark)
(b) At moment B the trampoline surface has been stretched downwards. State the effect of force that this shows, and name the force that the stretched surface now exerts on the ball. (2 marks)
(c) Using the effects of a force, explain how the ball comes to be moving upwards at moment C. (2 marks)
(a)Gravitational force — the pull of the Earth on the ball, acting towards the centre of the Earth. (This is the ball's weight.)
(b)Effect: a force can change the shape of an object — the ball pressing down stretches the trampoline surface. Force: elastic spring force, exerted upwards on the ball.
(c)The elastic spring force acts upwards on the ball. It first slows the falling ball down and stops it, and then changes the direction of its motion, pushing it upwards and speeding it up — so at moment C the ball is travelling upwards.
Gravity pulls down · Stretching = change of shape · Elastic spring force pushes back
Part (c) says "using the effects of a force" — so name them. "The trampoline is springy, so the ball bounces" describes what you see and earns no marks. Notice that one force does three jobs in a single bounce: it slows the ball, stops it, then changes the direction it moves in.
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