Types of force

Learn it by playing

Answer these questions to earn energy, then fish and explore. No account needed.

For teachers: ready-to-use lesson slides, revision notes, diagrams for Types of force (KS3 Science, Physics) — use them in your lesson, or run the topic as an interactive class activity your students play as a live game.

Lesson notes

Contact vs Non-Contact Forces

**Contact forces** act when two objects are physically touching.
**Non-contact forces** act between objects that are not touching.
Examples of contact forces: air resistance, friction, normal reaction, tension, thrust, upthrust.
Examples of non-contact forces: gravitational, magnetic, weight.

Contact Forces

**Air resistance** is a contact force that opposes motion through air.
**Friction** is a contact force that opposes motion when two surfaces rub together.
**Normal reaction** is a contact force acting perpendicular to a surface, opposing weight.
**Tension** is a contact force in a rope or cable being pulled.
**Thrust** is a contact force produced by an engine or rocket, pushing forwards.
**Upthrust** is an upward contact force that allows objects to float in fluids.

Non-Contact Forces

**Gravitational force** is an attractive non-contact force between any two masses.
**Magnetic force** is a non-contact force from magnetic fields; can attract or repel.
**Weight** is a non-contact force due to gravity acting on an object's mass.

Balanced and Unbalanced Forces

Balanced forces are equal in size and opposite in direction, resulting in no change in motion.
If forces are balanced, an object's speed remains constant (or stays at rest).
If the forward force (thrust) is greater than the backward force (friction + air resistance), the object accelerates.

Particle arrangement in solids, liquids, and gases – relevant to understanding how contact forces (e.g., friction) arise from particle interactions.

Slides

Step through every slide for this topic — plus flashcards and revision notes — with a free account.

Practice questions

Free preview — 8 of 40 questions. Sign up to see them all.

1.Which of the following is a non-contact force?
Easy
- AGravitational force
- BFriction
- CAir resistance
- DTension
2.Which force allows objects to float in a fluid?
Easy
- AUpthrust
- BWeight
- CThrust
- DNormal reaction
3.Friction is a type of:
Easy
- Acontact force
- Bnon-contact force
- Cmagnetic force
- Dgravitational force
4.Which of the following statements is true?
Easy
- AWeight is a non-contact force.
- BWeight is a contact force.
- CWeight is a type of friction.
- DWeight is a magnetic force.
5.Air resistance acts:
Medium
- Aagainst the direction of motion
- Bin the direction of motion
- Cperpendicular to the direction of motion
- Donly when an object is stationary
6.Which force is produced by an engine or rocket?
Medium
- AThrust
- BTension
- CUpthrust
- DNormal reaction
7.A skydiver falling through the air experiences two main forces. Which are they?
Medium
- AWeight and air resistance
- BWeight and upthrust
- CThrust and friction
- DTension and normal reaction
8.If two forces on an object are balanced, what happens to the object's speed?
Medium
- AIt remains constant
- BIt increases
- CIt decreases
- DIt becomes zero

Revision notes

## Types of Force Forces can be **contact** or **non-contact**. - **Contact forces**: act when objects are physically touching. - **Friction**: rubbing together, opposes motion. - **Air resistance**: opposes motion through air. - **Normal reaction**: perpendicular to surface, opposes weight. - **Tension**: in a rope/cable being pulled. - **Thrust**: from engine/rocket (e.g., car forward force). - **Upthrust**: upward force allowing floating. - **Non-contact forces**: act without touching. - **Gravitational force**: attraction between masses. - **Magnetic force**: attraction/repulsion from magnetic fields. - **Weight**: gravitational force on an object (downwards on Earth). ### Key Points - Friction and air resistance **act against direction of motion**. - Normal reaction is **equal and opposite** to the force pressing on a surface. - Balanced forces mean no change in speed; if forward force > backward force, speed increases.

Contact force: A force that acts when two objects are physically touching each other.
Non-contact force: A force that acts between objects that are not touching each other.
Air resistance: Contact force caused when an object travels through air; acts against the direction of motion.
Friction: Contact force caused by two objects rubbing together; acts against the direction of motion.
Gravitational force: Attractive non-contact force; any two objects with mass experience gravitational forces towards each other.
Magnetic force: Non-contact force caused by magnetic fields; can be attractive or repulsive.
Normal reaction: Contact force that is in opposition to another force; acts at 90 degrees to the surface of the object.
Tension: Contact force in a rope or cable being pulled.
Thrust: Contact force produced by an engine or rocket.
Upthrust: Upwards contact force that allows objects to float.
Weight: Non-contact force due to gravity; all objects on Earth have a downwards weight.

Flashcards

What are the two categories of force?

Contact forces and non-contact forces.

What is a contact force?

A contact force acts when two objects are physically touching each other.

What is a non-contact force?

A non-contact force acts between objects that are not touching each other.

Give an example of a contact force.

Friction, air resistance, normal reaction, tension, thrust, or upthrust.

Give an example of a non-contact force.

Gravitational force, magnetic force, or weight.

What is air resistance?

A contact force caused when an object travels through air; it acts against the direction of motion.

What is friction?

A contact force caused by two objects rubbing together; it acts against the direction of motion.

What is gravitational force?

An attractive non-contact force that acts between any two objects with mass.

What is magnetic force?

A non-contact force caused by magnetic fields; it can be attractive or repulsive.

What is normal reaction force?

A contact force that opposes another force and acts at 90° to the surface.

What is tension?

A contact force in a rope or cable being pulled.

What is thrust?

A contact force produced by an engine or rocket.

What is upthrust?

An upwards contact force that allows objects to float.

What is weight?

A non-contact force due to gravity; all objects on Earth have a downwards weight.

True or false: Friction is a non-contact force.

False. Friction is a contact force.

True or false: Weight is a contact force.

False. Weight is a non-contact force.

True or false: Thrust is the force that allows objects to float.

False. Upthrust allows objects to float; thrust is produced by an engine or rocket.

True or false: Air resistance acts against the direction of motion.

True.

What does it mean when two forces are balanced?

Balanced forces are equal in size and opposite in direction, resulting in no change in motion.

If the forwards force on a car is greater than the backwards force, what happens to its speed?

The speed of the car increases.

Name the downwards force on a skydiver.

Weight (due to gravity).

Name the upwards force on a skydiver falling through air.

Air resistance.

Unlock all 40 questions, flashcards & more

Create a free account to see every question, the slides, flashcards and revision notes for this topic.

Past papers

Past-paper practice for this topic is coming soon.

Coming soon