Scalars vectors and forces - Teacher Slides.pptx

AQA GCSE PHYSICS · PAPER 2 · FOUNDATION & HIGHER

Scalars, vectors and forces

Forces

Lesson 1 of 20

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AQA GCSE PHYSICS · PAPER 2 · FOUNDATION & HIGHER

Warm-up

Forces

Lesson 1 of 20

Answer each one, then check.

1

What is a force?

2

What is the unit of force?

3

Give an example of a quantity with direction.

4

What is friction?

5

What does a longer arrow mean on a force diagram?

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AQA GCSE PHYSICS · PAPER 2 · FOUNDATION & HIGHER

Warm-up - Answers

Forces

Lesson 1 of 20

1

What is a force?

A push or a pull

2

What is the unit of force?

The newton (N)

3

Give an example of a quantity with direction.

Velocity

4

What is friction?

A force that opposes motion between surfaces

5

What does a longer arrow mean on a force diagram?

A bigger force

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AQA GCSE PHYSICS · PAPER 2 · FOUNDATION & HIGHER

Learning Objectives

Forces

Lesson 1 of 20

1

Distinguish scalar quantities from vector quantities.

2

Represent a vector using an arrow.

3

Describe contact and non-contact forces with examples.

4

Describe the interaction between pairs of objects that produce a force on each object.

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AQA GCSE PHYSICS · PAPER 2 · FOUNDATION & HIGHER

Forces

Lesson 1 of 20

SCALARS AND VECTORS

Scalar quantities have magnitude only. Vector quantities have magnitude and direction.

A vector is drawn as an arrow: the length shows the magnitude and the arrowhead shows the direction. Force is a vector quantity.

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AQA GCSE PHYSICS · PAPER 2 · FOUNDATION & HIGHER

Forces as Vectors

Forces

Lesson 1 of 20

The longer the arrow, the larger the force.

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AQA GCSE PHYSICS · PAPER 2 · FOUNDATION & HIGHER

Scalar or Vector?

Forces

Lesson 1 of 20

Learn which is which.

Scalar (size only)

Vector (size and direction)

Distance

Displacement

Speed

Velocity

Mass

Force and weight

Energy, time, temperature

Acceleration and momentum

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AQA GCSE PHYSICS · PAPER 2 · FOUNDATION & HIGHER

Contact or Non-contact?

Forces

Lesson 1 of 20

CONTACT FORCES (OBJECTS TOUCHING)

• Friction.

• Air resistance.

• Tension.

• Normal contact force.

NON-CONTACT FORCES (OBJECTS SEPARATED)

• Gravitational force.

• Electrostatic force.

• Magnetic force.

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AQA GCSE PHYSICS · PAPER 2 · FOUNDATION & HIGHER

Drawing a Force Vector

Forces

Lesson 1 of 20

Draw an arrow to represent a force of 6 N to the right. Use a scale of 1 cm = 2 N.

1

Length

6 ÷ 2 = 3 cm

2

Direction

An arrowhead pointing right

ANSWER

A 3 cm arrow pointing to the right.

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AQA GCSE PHYSICS · PAPER 2 · FOUNDATION & HIGHER

Interaction Pairs

Forces

Lesson 1 of 20

Two magnets are brought close together with their north poles facing. Describe the forces.

1

Force on each magnet

Each magnet exerts a force on the other

2

Direction

Like poles repel, so each force points away from the other magnet

3

Type

Non-contact, because the magnets are not touching

ANSWER

Each magnet pushes the other away: equal and opposite non-contact forces.

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AQA GCSE PHYSICS · PAPER 2 · FOUNDATION & HIGHER

Key Points

Forces

Lesson 1 of 20

Use the right words.

Force is a vector

It has a size in newtons and a direction.

Pairs of forces

When two objects interact, each exerts a force on the other.

Scale

Choose a scale so the arrows fit on the page.

Examples

Name the force and its direction: 'friction to the left'.

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AQA GCSE PHYSICS · PAPER 2 · FOUNDATION & HIGHER

Key Terms

Forces

Lesson 1 of 20

Scalar

A quantity with magnitude only.

Vector

A quantity with magnitude and direction.

Contact force

A force between objects that are touching.

Non-contact force

A force between objects that are separated.

Magnitude

The size of a quantity.

Newton

The unit of force.

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AQA GCSE PHYSICS · PAPER 2 · FOUNDATION & HIGHER

Forces

Lesson 1 of 20

YOUR TASK

Sort Them

8 minutes

Sort into scalar and vector: mass, velocity, distance, acceleration, time, force. Then say whether each of these forces is contact or non-contact: friction, gravity, magnetic force, tension.

1

Does it have direction?

2

Are the objects touching?

WHAT A GOOD ANSWER SHOWS

Scalars: mass, distance, time. Vectors: velocity, acceleration, force. Contact: friction, tension. Non-contact: gravity, magnetic force.

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AQA GCSE PHYSICS · PAPER 2 · FOUNDATION & HIGHER

Can I...?

Forces

Lesson 1 of 20

Define scalar and vector.

Give examples of each.

Draw a vector arrow to scale.

List contact forces.

List non-contact forces.

Describe an interaction pair.

Use the word magnitude.

Write force directions.

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AQA GCSE PHYSICS · PAPER 2 · FOUNDATION & HIGHER

Summary & Exam Focus

Scalar: magnitude only. Vector: magnitude and direction.

Force is a vector.

Contact: friction, tension, air resistance, normal contact force.

Non-contact: gravity, electrostatic, magnetic.

EXAM FOCUS

State whether velocity is a scalar or a vector quantity. (1 mark)

Vector: it has direction.

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AQA GCSE PHYSICS · PAPER 2 · FOUNDATION & HIGHER

Exam Practice: Scalars, vectors and forces

Forces

Lesson 1 of 20

Answer all questions. Use the mark allocation as a guide to how much to write. · 13 minutes

Question 1 · 2 marks · State

Give one example of a scalar quantity and one example of a vector quantity.

Question 2 · 3 marks · Complete

Some forces are contact forces and some are non-contact forces. Give one example of each.

Question 3 · 2 marks · Draw

A force of 6 N acts to the right on an object. Draw an arrow to represent this force. Use a scale of 1 cm = 2 N.

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AQA GCSE PHYSICS · PAPER 2 · FOUNDATION & HIGHER

Exam Practice: Scalars, vectors and forces (cont.)

Forces

Lesson 1 of 20

Question 4 · 2 marks · Explain

Explain the difference between speed and velocity.

Question 5 · 3 marks · Describe

A book rests on a table. Describe the forces acting on the book. State the type of each force.

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AQA GCSE PHYSICS · PAPER 2 · FOUNDATION & HIGHER

Question 1 · 2 marks · State

Forces

Lesson 1 of 20

“

Give one example of a scalar quantity and one example of a vector quantity.

HOW TO ANSWER IT

Command word: State. Worth 2 marks, so plan before writing.

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AQA GCSE PHYSICS · PAPER 2 · FOUNDATION & HIGHER

Question 1 · mark scheme

Forces

Lesson 1 of 20

2 marks available. Award a mark for each point made.

A scalar quantity

1 mark

A vector quantity

1 mark

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AQA GCSE PHYSICS · PAPER 2 · FOUNDATION & HIGHER

Question 2 · 3 marks · Complete

Forces

Lesson 1 of 20

“

Some forces are contact forces and some are non-contact forces. Give one example of each.

HOW TO ANSWER IT

Command word: Complete. Worth 3 marks, so plan before writing.

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AQA GCSE PHYSICS · PAPER 2 · FOUNDATION & HIGHER

Question 2 · mark scheme

Forces

Lesson 1 of 20

3 marks available. Award a mark for each point made.

Contact example

1 mark

Non-contact example

1 mark

Correct link to touching or separated

1 mark

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AQA GCSE PHYSICS · PAPER 2 · FOUNDATION & HIGHER

Question 3 · 2 marks · Draw

Forces

Lesson 1 of 20

“

A force of 6 N acts to the right on an object. Draw an arrow to represent this force. Use a scale of 1 cm = 2 N.

HOW TO ANSWER IT

Command word: Draw. Worth 2 marks, so plan before writing.

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AQA GCSE PHYSICS · PAPER 2 · FOUNDATION & HIGHER

Question 3 · mark scheme

Forces

Lesson 1 of 20

2 marks available. Award a mark for each point made.

Length 3 cm

1 mark

Arrowhead pointing right

1 mark

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AQA GCSE PHYSICS · PAPER 2 · FOUNDATION & HIGHER

Question 4 · 2 marks · Explain

Forces

Lesson 1 of 20

“

Explain the difference between speed and velocity.

HOW TO ANSWER IT

Command word: Explain. Worth 2 marks, so plan before writing.

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AQA GCSE PHYSICS · PAPER 2 · FOUNDATION & HIGHER

Question 4 · mark scheme

Forces

Lesson 1 of 20

2 marks available. Award a mark for each point made.

Speed has no direction

1 mark

Velocity has direction

1 mark

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AQA GCSE PHYSICS · PAPER 2 · FOUNDATION & HIGHER

Question 5 · 3 marks · Describe

Forces

Lesson 1 of 20

“

A book rests on a table. Describe the forces acting on the book. State the type of each force.

HOW TO ANSWER IT

Command word: Describe. Worth 3 marks, so plan before writing.

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AQA GCSE PHYSICS · PAPER 2 · FOUNDATION & HIGHER

Question 5 · mark scheme

Forces

Lesson 1 of 20

3 marks available. Award a mark for each point made.

Weight downwards, non-contact gravitational

1 mark

Normal contact force upwards, contact

1 mark

Equal in size or balanced

1 mark

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