materials

Question 1

density

Answer 1

mass per unit volume

Question 2

hookes law

Answer 2

force is proportional to extension until the elastic limit (limit of proportionality

Question 3

elastic

Answer 3

extension returns to zero when load is removed

atoms can move small distances relative to their equilibrium positions
all energy stored as elastic strain energy

Question 4

elastic limit

Answer 4

maximum force a spring can withstand while returning to its original shape (without deformation)

Question 5

gradient of force against extension graphs

Answer 5

spring constant

Question 6

tensile forces

Answer 6

stretch an object
+ve stress
+ve strain

Question 7

compressive

Answer 7

compress an object
-ve stress
-ve strain

Question 8

stiffer springs

Answer 8

higher spring constant

Question 9

stress

Answer 9

F/A
Pa Nm-2
causes strain

Question 10

strain

Answer 10

ΔL/L
no units (ratio)

Question 11

energy

Answer 11

area under graph

Question 12

volume of sphere

Answer 12

4/3 π r3

Question 13

volume of cylinder

Answer 13

πr2h

Question 14

hysteresis

Answer 14

energy absorbed = energy between two routes
energy absorbed deforming molecules
elastic strands
elastomer
some parts remain deformed
rubber

Question 15

plastic behaviour

Answer 15

permanent deformation under stress
occurs after elastic limit

work done to separate atoms, energy mostly dissipated as heat

Question 16

brittle behaviour

Answer 16

breaks suddenly and fractures
very little plastic behaviour

Question 17

energy in spring systems

Answer 17

conservation of energy
total energy at all point in oscillation is the same

Question 18

elastic potential/strain energy

Answer 18

E=0.5Fx
sub in F= kx
using hookes law E= 0.5 kx2

Question 19

crumple zones

Answer 19

permanently deformed
redirect energy away from passengers

Question 20

parallel springs

Answer 20

suspension systems absorb more energy
higher spring constant

Question 21

youngs modulus

Answer 21

stress-strain ratio

Question 22

series springs

Answer 22

both extend same amount
lower overall spring constant ─

Question 23

stress to strain stiff materials

Answer 23

small strain to large stress

Question 24

gradient of stress-strain graph

Answer 24

young’s modulus

Question 25

determining young’s modulus experiment

Answer 25

calculate diameter of wire using micrometer
3 different places, mean
gives cross sectional area
clamp, pulley, mass hanger, meter ruler, tape, masses
measure initial length of wire/ distance between fixed end of wire and tape marker
increase weight in 50g intervals up to 700g recording extension
plot graph

long,thin wire reduces uncertainty by extending more for a given force

Question 26

yield point

Answer 26

material stretches without extra load. large amount of plastic deformation with constant/reduced load

Question 27

brittle

Answer 27

strong
little stress for high strain
fractures suddenly with little to no plastic deformation

Question 28

strong

Answer 28

not ductile e.g. stretch very little and break suddenly
high breaking stress

Question 29

ductile

Answer 29

necking occurs after elastic limit

Question 30

stiff

Answer 30

requires large force to produce small deformation

Question 31

tough

Answer 31

absorbs energy by deforming plastically, the tougher the material, the more plastic deformation

Question 32

malleable

Answer 32

will undergo significant plastic deformation under small stress

Question 33

endurance

Answer 33

ability to withstand repeated stress cycling

Question 34

strength

Answer 34

maximum stress before failing

Question 35

resilience/ elasticity

Answer 35

ability to spring back into shape

Question 36

breaking stress

Answer 36

stress large enough to break a material