1.5.3

Centre of gravity

Cambridge IGCSE Physics (0625)  · Unit 1: Motion, forces and energy  · 6 flashcards

Centre of gravity is topic 1.5.3 in the Cambridge IGCSE Physics (0625) syllabus , positioned in Unit 1 — Motion, forces and energy , alongside Physical quantities and measurement techniques, Motion and Mass and weight.  In one line: The centre of gravity of an object is the point through which its entire weight appears to act.

This topic is examined in Paper 1 (multiple-choice) and Papers 3/4 (theory), plus Paper 5 or Paper 6 (practical / alternative to practical).

The deck below contains 6 flashcards — 1 definition — covering the precise wording mark schemes reward.  Use the definition card to lock down command-word answers (define, state), then move on to the concept and application cards to handle explain, describe and compare questions.

Key definition

State what is meant by the centre of gravity of an object

The centre of gravity of an object is the point through which its entire weight appears to act.

What the Cambridge 0625 syllabus says

Official 2026-2028 spec

These are the exact learning objectives Cambridge sets for this topic. Match the command word (Describe, Explain, State, etc.) in your answer to score full marks.

  1. State State what is meant by centre of gravity
  2. Describe Describe an experiment to determine the position of the centre of gravity of an irregularly shaped plane lamina
  3. Describe Describe, qualitatively, the effect of the position of the centre of gravity on the stability of simple objects
Definition Flip

State what is meant by the centre of gravity of an object.

Answer Flip

The centre of gravity of an object is the point through which its entire weight appears to act.

Key Concept Flip

A delivery van is loaded such that its centre of gravity is too high. Explain how this might affect the stability of the van, especially when turning.

Answer Flip

A high centre of gravity makes the van less stable. When turning, the van may tilt. A higher centre of gravity means the weight force acts further from the pivot point (the wheels on the inside of the turn), increasing the turning moment. If this moment is large enough, the van could topple over.

Key Concept Flip

Describe an experiment to determine the centre of gravity of an irregularly shaped plane lamina.

Answer Flip

1. Hang the lamina from a point near the edge, allowing it to swing freely.
2. Hang a plumb line from the same point.
3. Trace the line of the plumb line onto the lamina.
4. Repeat steps 1-3, hanging the lamina from a *different* point.
5. The centre of gravity is the point where the two lines intersect. The lamina will balance if supported at this point.

Key Concept Flip

State *one* practical reason why it is important to accurately determine the center of gravity of a vehicle when designing it.

Answer Flip

Accurately determining the centre of gravity ensures the vehicle is stable, preventing it from easily tipping over, especially during turns or on uneven surfaces.

*Reason: Stability*

Key Concept Flip

Explain how the position of the centre of gravity affects the stability of an object. Use the example of a double-decker bus.

Answer Flip

A lower centre of gravity increases stability. In a double-decker bus, if the centre of gravity is too high, the bus is more likely to topple over during a turn because the line of action of the weight force will fall outside the base of support. Lowering the centre of gravity makes the bus more stable because a greater tilt is required for the line of action of the weight to fall outside the base.

Key Concept Flip

A toy vehicle has a centre of gravity that is 4.0 cm above the ground. State how placing a 20g weight at a height of 2.0 cm above the ground would affect the vehicle's stability.

Answer Flip

Placing the weight lower down will lower the overall centre of gravity. This increases the stability of the vehicle, making it less likely to topple over. Because the centre of gravity will be lower to the ground than 4.0cm.

Review the material

Read revision notes with definitions, equations, and exam tips.

Read Notes

Test yourself

Practice with MCQ questions to check your understanding.

Take Physics Quiz
1.5.2 Turning effect of forces 1.6 Momentum

Key Questions: Centre of gravity

State what is meant by the centre of gravity of an object.

The centre of gravity of an object is the point through which its entire weight appears to act.

More topics in Unit 1 — Motion, forces and energy

Centre of gravity sits alongside these Physics decks in the same syllabus unit. Each uses the same spaced-repetition system, so progress in one informs the next.

Key terms covered in this Centre of gravity deck

Every term below is defined in the flashcards above. Use the list as a quick recall test before your exam — if you can't define one of these in your own words, flip back to that card.

What is meant by the centre of gravity of an object

Related Physics guides

Long-read articles that go beyond the deck — cover the whole subject's common mistakes, high-yield content and revision pacing.

How to study this Centre of gravity deck

Start in Study Mode, attempt each card before flipping, then rate Hard, Okay or Easy. Cards you rate Hard come back within a day; cards you rate Easy push out to weeks. Your progress is saved in your browser, so come back daily for 5–10 minute reviews until every card reads Mastered.