[AS] Materials

Question 1

What is Hooke’s Law?

Answer 1

F = kL

Question 2

What is the point at which Hooke’s Law stops working?

Answer 2

The limit of proportionality, P

Question 3

After what point is the material permanently stretched?

Answer 3

The Elastic Limit, E

Question 4

After the load is released, what happens to an elastically deformed material?

Answer 4

The material returns to its originally shape

The atoms return to their equilibrium position

Question 5

After the load is released, what happens to an plastically deformed material?

Answer 5

The material is permanently stretched

The atoms don’t return to their original position

Question 6

If a deformation is elastic, what happens to the work done?

Answer 6

It is stored as elastic strain energy

Question 7

What is the question for tensile stress?

Answer 7

(Force) divided by (cross-sectional area)

Question 8

What is the equation for tensile strain?

Answer 8

(Change in length) divided by (original length)

Question 9

What is a stress big enough to break a material called?

Answer 9

Breaking stress

Question 10

What is the ultimate tensile strength (UTS)?

Answer 10

The maximum stress that the material can withstand.

Question 11

What is the area under a force-extension graph?

Answer 11

Elastic strain energy

Question 12

How do you calculate energy stored in a stretched material?

Answer 12

E = ½Fdx
E = ½kdx^2

Question 13

What is the units for the Young Modulus?

Answer 13

Nm^-2

Question 14

How do you calculate the Young Modulus?

Answer 14

Stress over strain

Question 15

What is the Young Modulus a measurement of?

Answer 15

Stiffness

Question 16

What does a high Young Modulus indicate?

Answer 16

High stiffness

Question 17

What is the gradient of a stress-strain graph?

Answer 17

Young Modulus

Question 18

What is the area under a stress-strain graph?

Answer 18

Energy per unit volume

Question 19

What is the equation for energy per unit volume?

Answer 19

½ x stress x strain

Question 20

What are the units for energy per unit volume?

Answer 20

Jm^-3

Question 21

Define brittle

Answer 21

Material breaks suddenly without deforming plastically

Question 22

Define ductile

Answer 22

Material can be drawn into wires without losing strength

Question 23

Define strong

Answer 23

Material can withstand high stress (a lot of force) without deforming or breaking

Question 24

Define hard

Answer 24

Material is very resistant to cutting, indentation and abrasion

Question 25

Define stiff

Answer 25

Material has a high resistance to bending and stretching

Question 26

Define tough

Answer 26

Material can absorb a lot of energy before breaking

Question 27

What is the area between the loading and unloading curves for a stress-strain graph of rubber?

Answer 27

Amount of energy converted to heat per unit volume

Question 28

How do you calculate elastic strain energy from a graph?

Answer 28

the area under a force-extension graph

Question 29

How do you calculate energy per unit volume from a graph?

Answer 29

the area under a stress-strain graph

Question 30

How do you calculate Young Modulus from a graph?

Answer 30

the gradient of a stress-strain graph

Question 31

What is the structure of a metal?

Answer 31

Metal ions in a “sea” of free electrons

forming metallic bonds

Question 32

What structural terms describe metals?

Answer 32

Tough; Ductile

Question 33

What structural term describes ceramics?

Answer 33

Brittle; Stiff