# 3.4 Materials Flashcards Preview

## Physics A Level > 3.4 Materials > Flashcards

Flashcards in 3.4 Materials Deck (18)
1
Q

What do tensile forces cause?

A

Tensile deformation

2
Q

What do compressive forces cause?

A

Compressive deformation

3
Q

What is Hooke’s Law? (2)

A

For forces less than the elastic limit of a spring, the extension is directly proportional to the force applied
F = kx

4
Q

What does the force-extension graph of a spring show? (2)

A

Straight line from origin to elastic limit - elastic deformation
Begins to curve - plastic deformation

5
Q

What is elastic deformation?

A

The material will return to its original shape when the force is removed

6
Q

What is plastic deformation?

A

Permanent structural changes mean that the material will not return to its original shape when the force is removed

7
Q

What is the work done in a spring transferred to? (2)

A

Elastic potential energy

Fully recoverable due to elastic behaviour of spring

8
Q

What does the area under a force-extension graph represent?

A

Work done

9
Q

How is elastic potential energy calculated?

A

1/2 Fx

1/2 kx^2

10
Q

What is tensile stress? (2)

A

Force applied per unit cross-sectional area of wire

σ = force / cross-sectional area

11
Q

What is tensile strain? (2)

A

The fractional change in the length of the wire

ε = extension / original length

12
Q

What is a ductile material?

A

One that can be easily drawn into a wire or hammered into thin sheets (e.g. mild steel)

13
Q

What are upper and lower yield points?

A

The points between which the material extends rapidly

14
Q

What is ultimate tensile strength?

A

The maximum stress a material can withstand before it breaks

15
Q

What happens, for a ductile material, beyond the ultimate tensile strength? (2)

A

Necking - the material becomes longer and thinner at weakest point
Snaps at breaking point

16
Q

What is the breaking strength of a material?

A

The stress value at the point of fracture

17
Q

What is the Young modulus? (3)

A

The constant ratio of stress to strain within the limit of proportionality
Depends only on material, not shape or size
E = σ/ε

18
Q

What is a hysteresis loop? (2)

A