What is the difference between contact and non-contact forces, and how do objects interact at a distance?
Contact and non-contact forces: the difference between them, examples of each, and how objects can interact at a distance through fields.
A focused answer to Edexcel GCSE Physics 9.1 and 9.2, covering the difference between contact and non-contact forces, examples of each, how objects interact at a distance through gravitational, magnetic and electrostatic fields, and the vector and scalar distinction for forces.
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What this dot point is asking
Edexcel statements 9.1 and 9.2 want you to describe with examples how objects can interact at a distance without contact, the difference between contact and non-contact forces, and the difference between vector and scalar quantities as it applies to forces.
Contact forces
Contact forces are the everyday forces you can trace to a point of contact: the floor pushing up on your feet, a rope pulling a sledge, friction slowing a rolling ball. They disappear the moment the objects separate. Recognising the named contact forces (friction, air resistance, tension, normal contact) is what examiners look for.
Non-contact forces
Non-contact forces are surprising because they act across a gap: the Earth pulls the Moon without a rope, a magnet attracts a paperclip before they touch, and a charged balloon attracts your hair from a distance. These three (gravitational, magnetic, electrostatic) are the non-contact forces you must know.
Interacting at a distance through fields
The field is the way physics explains action at a distance. The source object (a mass, a magnet or a charge) fills the space around it with a field, and any suitable object in that field feels a force. This idea returns in magnetism (magnetic fields) and static electricity (electric fields).
Forces as vectors
Because forces are vectors, two forces of the same size in opposite directions cancel, while two in the same direction add. This vector nature underlies free-body diagrams, resultant forces and moments, which are the rest of the topic.
How Edexcel examines this
This dot point is examined on both tiers, usually as a short definition or classification question worth two or three marks. The mark scheme rewards the touching-versus-at-a-distance distinction and a valid example of each type, with the named contact forces (friction, air resistance, tension, normal contact) and the three non-contact forces (gravitational, magnetic, electrostatic). A common item asks how objects interact at a distance, rewarding the idea of a field as a region where a force acts without contact, plus two non-contact examples. The most penalised error is classifying gravity (or magnetism) as a contact force, so anchor those firmly as non-contact. You may also be asked to identify the forces acting in a labelled situation (which sets up free-body diagrams) or to state that forces are vectors, which connects to resultant forces. Keep the field idea ready for the magnetism and static electricity topics, where the same concept reappears.
Try this
Q1. Give one example of a non-contact force. [1 mark]
- Cue. Gravitational force (or magnetic, or electrostatic).
Q2. State what is needed for a contact force to act. [1 mark]
- Cue. The two objects must be touching.
Exam-style practice questions
Practice questions written in the style of Pearson Edexcel exam questions on this dot point, with worked answer explainers. The year tag is the paper they imitate, not the source.
Edexcel 20203 marksExplain the difference between a contact force and a non-contact force, and give one example of each.Show worked answer →
A contact force acts only when two objects are physically touching, for example friction, air resistance, tension or the normal contact force (1 mark for the definition, 1 mark for a contact example). A non-contact force acts at a distance, without the objects touching, for example the gravitational force, the magnetic force or the electrostatic force (1 mark for a non-contact example). Markers reward the touching-versus-at-a-distance distinction and a valid example of each. Calling gravity a contact force is the usual error.
Edexcel 20223 marksDescribe how two objects can interact at a distance without touching, using the idea of a field, and give two examples of such forces.Show worked answer →
Objects can interact at a distance because each one creates a field (a region in which a force is felt) around it, and another object placed in the field experiences a force (1 mark). Examples of non-contact forces that act through fields are gravitational force (through a gravitational field), magnetic force (through a magnetic field) and electrostatic force (through an electric field) (2 marks for two valid examples). Markers reward the idea of a field as a region where a force acts at a distance, and two correct non-contact force examples.
Related dot points
- Resolving and resultant forces: combining forces into a resultant, using scale vector diagrams, and resolving a single force into perpendicular components.
A focused answer to Edexcel GCSE Physics 9.3, covering how to find the resultant of forces, adding forces along a line, using scale vector diagrams (the parallelogram or tip-to-tail method) for forces at an angle, and resolving a single force into perpendicular components.
- Scalar and vector quantities: the difference between magnitude-only scalars and vectors that also have direction, and classifying the key physical quantities.
A focused answer to Edexcel GCSE Physics 2.1 to 2.5, covering the difference between scalar and vector quantities, classifying displacement, velocity, acceleration, force, weight, momentum and energy, and why velocity is speed in a stated direction.
Sources & how we know this
- Pearson Edexcel GCSE (9-1) Physics (1PH0) specification — Pearson (2016)