Work, Energy, Power And Materials

Question 1

State Hooke’s law

Answer 1

The extension is directly proportional to the load force provided that the elastic limit is not exceeded

Question 2

Define spring constant

Answer 2

Force/extension

Question 3

State the unit of spring constant

Answer 3

Nm^-1

Question 4

Define work done on a string

Answer 4

Average force x extension

Question 5

Define elastic behaviour

Answer 5

Returns to original shape and size when the load is removed

Question 6

Define plastic behaviour

Answer 6

Will not return to its original shape and size when the load is removed

Question 7

Define young modulus

Answer 7

Stress/strain (in proportional region)

Question 8

Define stress

Answer 8

Force/cross sectional area

Question 9

Define strain

Answer 9

Extension/original length

Question 10

Define ultimate tensile strength

Answer 10

The breaking stress of a material

Question 11

Ductile material

Answer 11

Initially elastic and obeys Hooke’s law
Shows plastic behaviour once elastic limit is exceeded
For example copper

Question 12

Brittle material

Answer 12

Obeys Hooke’s law and is elastic, breaks before it deforms plastically
Eg glass

Question 13

Polymeric material

Answer 13

Consists of long coiled
Chains
Can undergo much bigger strains than other materials