Materials

Question 1

Hookes law

Answer 1

‘Extension is directly proportional to the force applied’
Given that environmental factors are kept constant

Question 2

Limit of proportionality

Answer 2

Point after which Hooke’s law is no longer obeyed

Question 3

Elastic limit

Answer 3

Just after limit of proportionality and if you increase the force applied beyond this, the material will deform plastically

Question 4

Hooke’s law equation

Answer 4

F =k△L

Question 5

Tensile stress

Answer 5

Force applied per unit cross-sectional area

Question 6

Tensile strain

Answer 6

Caused by tensile stress, and is defined as the extension over original length

Question 7

Elastic strain energy

Answer 7

When work is done on a material to stretch or compress it
Found by calculating area under force-extension graphs
ESE = 1/2F△L

Question 8

Breaking stress

Answer 8

Value of stress at which the material will break apart, value depends on conditions

Question 9

Plastic

Answer 9

Where a material will experience a large amount of extension as the load is increased, especially beyond the elastic limit

Question 10

Brittle

Answer 10

This is where a material will extend very little and therefore likely to fracture at a low extension

Question 11

Stress-strain graphs

Answer 11

Describe the behaviour of a material
They show a materials ultimate tensile stress which is the highest point on the graph as it shows the max stress the material can withstand
Shape shows whether ductile, brittle or plastic

Question 12

Young’s modulus

Answer 12

Value that describes the stiffness of a material
Tensile stress / Tensile strain
E = FL/△LA

Question 13

Finding YM

Answer 13

Gradient of straight part of the graph