Pearson Edexcel International GCSE Physics · specification 4PH1 · Paper 2 | Whole paper: All content including bold P statements · Free · no account needed
1(c) Forces, movement, shape and momentum (4PH1 specification)
What forces do to bodies: change their motion, change their shape, and — in the Paper 2 statements — transfer momentum and turn things about a pivot.
Learn it on Incandio
The 8 Incandio pages that teach this — each explained in full, then proved in marked questions, taught back to an AI pupil and defended in a debate. Completely free.
- Forces, Vectors and Scalars — What a force actually does, why some quantities need a direction to mean anything, and why that makes a force one of them.
- Resultant Force, Friction and F = ma — Why a moving object stops, what really happens when you add forces up, and the one equation that connects force to motion.
- Weight and Terminal Velocity — What weight actually is, why it is not the same as mass, and what happens to a falling object once the air starts pushing back.
- Stopping Distance — Why a car does not stop when you decide to stop it — and which of the two distances each factor actually lengthens.
- Hooke's Law and Elasticity — Why a spring stretches in proportion to the force — until, quite suddenly, it does not.
- Momentum — Why a slow lorry is harder to stop than a fast bicycle — and why every safety device ever designed does the same one thing.
- Conservation of Momentum — The bookkeeping rule that survives every collision — and why a force is really a rate of change of momentum.
- Moments and Centre of Gravity — Why a spanner works better when it is longer, where an object's weight can be said to act, and how two supports share a load.
The teaching route this belongs to: Topic 1 · Forces and motion (Physics) — the lessons in order, with every gate.
Specification coverage
Topic 1 Forces and motion (c) Forces, movement, shape and momentum — statements 1.11–1.36P (includes bold P statements assessed on Paper 2 only)
Assessment objectives: AO1, AO2, AO3. Suggested learning time: 110 minutes.
Required knowledge
- The effects of forces between bodies: changes in speed, shape or direction
- Different types of force, such as gravitational and electrostatic
- How vector quantities differ from scalar quantities, and that force is a vector
- Calculate the resultant of forces acting along a line
- Friction as a force that opposes motion
- force = mass × acceleration
- weight = mass × gravitational field strength
- Hooke's law and the behaviour of springs, including the limit of proportionality
- Bold P statements: momentum = mass × velocity, conservation of momentum, force = change in momentum ÷ time, and the principle of moments
Required skills
- Draw and interpret free-body force diagrams
- Resolve a problem into balanced and unbalanced forces
- Apply conservation of momentum to collisions (Paper 2)
- Apply the principle of moments to a balanced beam (Paper 2)
- Describe and evaluate the required practical: Investigate how extension varies with applied force for helical springs, metal wires and rubber bands.
How it is examined
- Multiple-choice and short-answer recall
- Calculations using the specification's relationships
- Extended open-response applying the physics to an unfamiliar situation
- Practical questions on method, variables, results and sources of error
Common mistakes
- Confusing mass and weight. Mass is in kilograms and does not change with location; weight is a force in newtons and does.
- Assuming Hooke's law holds indefinitely. Beyond the limit of proportionality the graph curves and the relationship fails.
- Forgetting momentum is a vector. In a head-on collision one velocity must be negative.
- Taking the distance in a moment calculation along the beam rather than perpendicular to the force.
This page maps the specification. The pages above teach it, and the Physics lessons hold the whole course — completely free.