How to Revise Topic 1: Motion, Forces and Energy

Topic 1 is the largest topic in IGCSE Physics and carries the most marks. This guide breaks it down into manageable revision blocks.

What Topic 1 covers

Topic 1 has eight subtopic areas:

1. Physical quantities and measurement (SI units, scalars and vectors, measurement instruments)
2. Motion (speed, velocity, acceleration, distance-time and velocity-time graphs)
3. Forces (types of forces, resultant force, Newton’s laws, friction, Hooke’s Law)
4. Momentum (momentum calculations, conservation of momentum, collisions)
5. Energy, work and power (energy stores and transfers, work done, power, efficiency)
6. Pressure (pressure in solids, liquids and gases, manometers)
7. Density (density calculations, floating and sinking)
8. Energy resources (renewable and non-renewable sources, environmental impact)

Priority areas (highest mark density)

Based on past paper analysis, these subtopics appear most frequently:

Must-know calculations

• speed = distance / time, and velocity-time graph analysis
• F = ma (Newton’s second law)
• momentum = mass x velocity, and conservation of momentum
• work = force x distance
• power = work / time
• KE = 0.5mv^2, GPE = mgh
• pressure = force / area, pressure in liquids = density x g x depth
• density = mass / volume
• moment = force x perpendicular distance
• efficiency = useful output / total input x 100%

Must-know concepts

• The difference between speed and velocity (scalar vs vector)
• Reading and interpreting distance-time and velocity-time graphs
• Newton’s three laws and how to apply them
• The difference between mass and weight
• Conservation of energy in real systems
• How braking distance depends on speed and road conditions

Revision strategy for Topic 1

Week 1: Motion and forces (the mathematical core)

• Day 1: Speed, velocity and acceleration definitions. Practise s = vt and a = (v-u)/t.
• Day 2: Distance-time graphs (gradient = speed) and velocity-time graphs (gradient = acceleration, area = distance).
• Day 3: Forces, resultant force, F = ma calculations.
• Day 4: Newton’s laws in context. Free-body diagrams.
• Day 5: Mixed questions from past papers on motion and forces.

Week 2: Energy, momentum and pressure

• Day 1: Energy stores, KE and GPE calculations.
• Day 2: Work, power and efficiency.
• Day 3: Momentum and conservation of momentum in collisions.
• Day 4: Pressure in solids and liquids. Manometers.
• Day 5: Mixed past paper questions on energy, momentum and pressure.

Common mistakes in Topic 1

• Confusing distance-time and velocity-time graphs (reading speed from a v-t graph when the question shows a d-t graph).
• Forgetting to convert units (km/h to m/s: divide by 3.6).
• Using the wrong Newton’s law (students often describe the third law when the question asks about the first or second).
• Calculating momentum but forgetting that direction matters (momentum is a vector).
• Not including units in calculation answers.

Self-test checklist

After revision, you should be able to:

• Calculate speed, velocity and acceleration from given data.
• Sketch and interpret d-t and v-t graphs.
• State and apply all three of Newton’s laws.
• Calculate resultant force and predict motion.
• Apply the principle of conservation of momentum.
• Calculate work, power and efficiency.
• Calculate pressure in solids and liquids.
• Explain the difference between renewable and non-renewable energy resources.