Intro to Forces

• Science
• Lower Secondary (Key Stage 3)

Intro to Forces

What do you already know about forces?

Types of Force

We split forces into two categories:

• Contact
• Non-contact

A person rubs their hands together to warm them up. What is the name of the force?

Friction (Contact)

A backwards acting force caused by two objects rubbing together.

What would be another example of friction?

A propeller helps to drive a boat forwards through the water. What is the name of the force?

Thrust (Contact)

A forwards acting force of one object pushing another.

What would be another example of thrust?

A boat floats on the ocean. What is the name of the force that stops it from sinking?

Upthrust (Contact)

An upwards acting force of a gas or liquid on an object.

What would be another example of upthrust?

A bullet fired underwater will quickly slow down. What is the name of the force?

Drag (Contact)

An upwards acting force of a gas or liquid on an object.

What would be another example of upthrust?

Tension (Contact)

A force where 2 objects pull against each other.

Weight/Gravity (Non-contact)

A downwards acting caused by the pull of the planet.

What would be another example of weight?

A paperclip is pulled towards a fridge magnet. What is the name of the force?

Magnetism (Non-contact)

The pull/push a magnet exerts on any magnetic object within its field.

Thrust

1. Contact
2. Non-contact

Drag

1. Contact
2. Non-contact

Weight

1. Contact
2. Non-contact

Friction

1. Contact
2. Non-contact

Air resistance

1. Contact
2. Non-contact

Magnetism

1. Contact
2. Non-contact

Name 3 contact forces. Give an example of each force.

Match the force to the description.

Thrust

Weight

Drag

Tension

Friction

Upthrust

Which force is the biggest in this diagram?

1. Drag
2. Weight
3. Thrust

Which force is the biggest in this diagram?

1. Drag
2. Weight

Which force is the biggest in this diagram?

1. Thrust
2. Weight
3. Upthrust
4. Air resistance

Label the force diagram.

Weight

Friction

Drag

Thrust

Tension

Upthrust

Reaction force

Label the force diagram.

Weight

Friction

Drag

Thrust

Tension

Upthrust

Reaction force

Label the force diagram.

Weight

Friction

Drag

Thrust

Tension

Upthrust

Reaction force

Label the force diagram.

Weight

Friction

Drag

Thrust

Tension

Upthrust

Reaction force

What effects do forces have?

How can you tell each car is applying a force here?

How can you tell the dog is applying a force here?

What 3 effects can a force have on an object?