HOME PAGE * SEARCH * UK KS3 level Science Quizzes for students aged ~13-14

UK GCSE level Biology * Chemistry * Physics age ~14-16 * Advanced Level Chemistry age ~16-18

School-college Physics Notes: Forces Section 1.1 What is a force?

GCSE level Physics exam revision notes on forces

Forces 1: 1.1 What is a force?

The difference between contact and non-contact forces

[Author © Dr Phil Brown PhD: Doc Brown's physics exam revision notes suitable for students of UK IGCSE & GCSE level physics courses, ~ US grades 9-10 physics [forces-1 page updated Mar 10th 2026 *]

 email doc brown: problems?, comments? query? * [privacy policy and disclaimer]

[KEY POINTS and learning objectives for this page, after initial notes] * [email doc b] * [privacy]

INDEX of my physics notes on FORCES Section 1. An introduction

1.1a What is a force?

The first thing to say is you can't see a force!

BUT, you can observe its effect and often quantify it with equations.

The unit of force is the newton (N) and there are all sorts of forces e.g.

A force is a 'mechanical' push or pull effect, acting on an object when it interacts with something.

 

You can have forces of repulsion and attraction or from friction of objects/materials rubbing against each other etc.

The result of the interaction depends on the nature and magnitude of the forces involved.

The value of force can be very small or very large, from zero to an 'immeasurable' value at the centre of a black hole!

You are familiar with the results of electrical, magnetic or gravitational forces and mechanical forces such those acting in the spring of a clock, the engine of a road vehicle or the motion of planets.

You also will learn formulae to do calculations on gravity and acceleration.

 

Arrows are used on diagrams to show the direction and magnitude of a force

 but first check out you know the difference between scalar and vector quantities explained in section 1.2.

1.1b Comparing contact forces and non-contact forces

Forces between objects can be divided into two main categories.

The interactive forces involved when two objects are in physical contact - contact forces.

The interactive forces when the two objects are apart, non-contact forces, described as 'action at a distance force'.

Sometimes non-contact forces are acting between objects that are actually in contact e.g. you sitting in front of your computer is an example!

This involves gravity (non-contact) and weight and compression (contact forces).

See the flask standing on a bench example later parts of section1. on forces.

See 1.3 Comparing and explaining examples of contact forces

and 1.4 Comparing and explaining examples of non-contact forces

 

INDEX of my physics notes on FORCES Section 1. An introduction

Key points about FORCES - explaining the difference between contact forces and non-contact forces

Information sources for Doc Brown's key points: IGCSE-GCSE physics are based on textbooks & syllabus-specifications for students taking the UK AQA, Edexcel, OCR 21st Century Science, OCR Gateway science suite, WJEC, CCEA and CIE GCSE physics 9-1 level science examinations

A structured set of summary revision notes tailored to the major UK GCSE/IGCSE physics exam boards (WJEC, CCEA, CIE, AQA, Edexcel, OCR) on forces, including contact and non-contact forces. I’ve also included exam tips to help you master this topic.

What Is a Force?

  • A force is a push or pull acting on an object due to its interaction with another object.
  • Measured in Newtons (N).
  • Forces are vector quantities – they have both magnitude and direction.
  • Effects of forces:
    • Change in speed (acceleration or deceleration)
    • Change in direction
    • Change in shape (compression/stretching)

Contact Forces

These occur only when objects are physically touching.

Contact Force Description
Friction Opposes motion between two surfaces in contact
Air Resistance A type of friction acting against a moving object through air
Tension Force transmitted through a string, rope, cable when pulled
Normal Contact Force Perpendicular force exerted by a surface to support an object resting on it
Upthrust Upward force exerted by a fluid on an object submerged in it

Tip: Use diagrams to show direction of contact forces. Label arrows clearly with force names and directions.

Non-Contact Forces

These act without physical contact, through fields.

Non-Contact Force

Description
Gravitational Force Attraction between masses (e.g. Earth and objects)
Electrostatic Force Attraction/repulsion between charged particles
Magnetic Force Attraction/repulsion between magnetic poles

Tip: Always refer to gravitational force as weight in exam answers, not just “gravity”.

Typical Required Knowledge by Exam Boards

Key Requirements
Define force, distinguish contact/non-contact, examples, force diagrams
Effects of forces, resultant force, vector diagrams, examples of each force type
Force interactions, Newton’s laws, contact/non-contact forces
Types of forces, force diagrams, balanced/unbalanced forces
Force definitions, examples, resultant force, vector representation
Types of forces, effects, force diagrams, practical examples

Tip: Practice identifying forces in real-life scenarios (e.g. a book on a table, a parachute falling).

Force Diagrams & Resultant Force (for later sections of this topic)

  • Use arrows to represent forces:
    • Length = magnitude
    • Direction = direction of force
  • Resultant force: The overall force acting on an object.
    • If forces are balanced, resultant force = 0 → object stays still or moves at constant speed.
    • If unbalanced, object accelerates in direction of resultant force.

Student Tips for Exam Success

  • Learn definitions and examples for each force type.
  • Practice drawing force diagrams with correct labels.
  • Use real-world examples to explain concepts (e.g. magnet attracting iron nail).
  • Understand Newton’s Third Law: Every action has an equal and opposite reaction.
  • Avoid vague terms like “gravity” or “wind resistance” – use precise terminology like weight or air resistance.

Keywords, phrases and learning objectives for forces

Be able to explain what a force is and what can a force do?

Know the unit of force is a newton, N

In the interaction of objects with each other, know the difference between contact forces and non-contact forces

WHAT NEXT?

TOP of page

INDEX for physics notes on FORCES section 1

INDEX of all my physics notes on FORCES

INDEX of all my physics notes on FORCES and MOTION

INDEX of all my PHYSICS NOTES

email doc brown - comments - query?

BIG website and using the [SEARCH BOX] below, maybe quicker than navigating the many sub-indexes

HOME PAGE of Doc Brown's Science

Basic Science Quizzes for UK KS3 science students aged ~12-14, ~US grades 6-8

Biology * Chemistry * Physics for UK GCSE level students aged ~14-16, ~US grades 9-10

Advanced Level Chemistry for pre-university age ~16-18 ~US grades 11-12, K12 Honors

Find your GCSE/IGCSE science course for more help links to all science revision notes

importance of examples of contact & non-contact forces explained in GCSE level physics, What you need to know about examples of contact & non-contact forces explained for GCSE level physics, Explaining the use of examples of contact & non-contact forces explained knowledge in GCSE level physics, Examples of examples of contact & non-contact forces explained explained when studying GCSE level physics, What is significant about examples of contact & non-contact forces explained, describing the theory of examples of contact & non-contact forces explained when studying GCSE level physics, revision notes for examples of contact & non-contact forces explained in exams, online exam help for examples of contact & non-contact forces explained, revision notes about examples of contact & non-contact forces explained, what do I need to learn about examples of contact & non-contact forces explained for by GCSE physics exam? help to understand the examples of contact & non-contact forces explained topic in preparation for GCSE physics exam question, how to prepare for questions involving examples of contact & non-contact forces explained in a GCSE physics examination? Revision notes on what is a force? based on the syllabus-specifications for students taking IGCSE/GCSE level physics examinations, summary revision notes and key points on what is a force? for students taking the AQA igcse/gcse physics notes on what is a force?, Edexcel gcse physics notes on what is a force?,  OCR 21st century GCSE physics notes on what is a force?, OCR gateway GCSE physics notes on what is a force?, WJEC gcse physics notes on what is a force?, CCEA gcse physics notes on what is a force? for students taking CIE Cambridge igcse physics, exam revision notes on what is a force?, useful for US grade 9-10 physics courses

SITEMAP Website content © Dr Phil Brown 2000+. All copyrights reserved on Doc Brown's physics revision notes, images, quizzes, worksheets etc. Copying of website material is NOT permitted. Exam revision summaries and references to GCSE science course specifications are unofficial.

INDEX of my physics notes on FORCES Section 1. An introduction

TOP OF PAGE