materials

Question 1

what is deformation

Answer 1

We can apply stretching, compressing or twisting forces to an object that will result in it changing shape.

Question 2

what is plastic deformation

Answer 2

normally An elastic object will return to its original position once forces have been removed however if it experiences plastic deformation (reached its elastic limit) it will no longer be able to do this .

(permanent deformation )

Question 3

what is elastic limit ?

Answer 3

where an elastic object will either break or experience plastic deformation.
(can no longer go back to its original position without a force acting on it)

Question 4

Brittleness

Answer 4

how much it will shatter or crack when subjected to a shock.

Question 5

Strength

Answer 5

how much breaking stress it can withstand.

Question 6

Malleability

Answer 6

how easily it can be formed into thin sheets.

Question 7

Ductility

Answer 7

how easily it can be drawn into a wire.

Question 8

what is the unit for Force, F

Answer 8

N newtons

Question 9

what is the unit for spring constant, K

Answer 9

Newtons per meter , N/m

or Nm-1

Question 10

what is the unit for change in extension , Δx

Answer 10

Meters m

Question 11

what is hooke’s law ?

Answer 11

hooke’s law states that the relationship between force and extension is directly proportional

Question 12

what is the equation for hooke’s law ?

Answer 12

force= spring constant x extension

Question 13

what is the symbol for elastic energy (youngs modulus)

Answer 13

ΔE

Question 14

what is the unit for stress

Answer 14

Nm-2

Question 15

what is the unit for strain

Answer 15

there isn’t a unit

Question 16

what is the unit for young’s modulus ?

Answer 16

Nm-2

Question 17

what is the unit for cross section ?

Answer 17

m2

Question 18

what is the unit for length

Answer 18

m

Question 19

definition of stress

Answer 19

Stress is a measure of the force acting within a material.

Question 20

definition of strain

Answer 20

Strain is the extension of the material compared to its original length. This is the result of stress.

Question 21

definition of the young’s modulus

Answer 21

The Young modulus is a constant of proportionality that shows the stiffness of the material.

Question 22

what is the elastic region on a Stress strain curve?

Answer 22

the section before an object reaches its elastic limit

Question 23

what happens to the object in the elastic region?

Answer 23

• the bonds between atoms increase in length due to the forces acting on them, if the force is removed then they return to their original shape (equilibrium positions)

Question 24

what is the plastic region?

Answer 24

beyond the elastic limit

Question 25

what happens in the plastic region?

Answer 25

- the arrangement of atoms changes - the object experiences plastic deformation - the object may contract however it will not revert to its equilibrium position

Question 26

Creep

Answer 26

when materials under stress deform gradually over time. This is more severe for materials that have been subject to high heats for a long period of time.

Question 27

fatigue

Answer 27

the embrittlement and failure of a material that occurs with relatively low levels of stress, if these are repeatedly applied and relaxed over many cycles

Question 28

what does dissipated mean?

Answer 28

lost to surroundings

Question 29

what is elastic hysteresis?

Answer 29

some materials require more energy to load the material with stress than they do for unloading it (the energy is unequal). Energy is therefore dissipated into the surroundings as heat when unloading, which is why there is a difference.

Question 30

on a stress-strain graph what will the line look like for a material with a high young's modulus ?

Answer 30

it will be a steep line (stiffness)

Question 31

how with the line look on a stress-strain graph if the material is brittle?

Answer 31

- the line will be very short after the elastic limit

Question 32

density

Answer 32

os the mass per unit volume

Question 33

density in solids and liquids is considered ....

Answer 33

fixed

Question 34

g to kg=

Answer 34

divided by 1000

Question 35

mg to g

Answer 35

divided by 1000

Question 36

mg to kg

Answer 36

divided by 1000 then divided by 1000 again

Question 37

volume =(cube)

Answer 37

hight x width x length

Question 38

volume = (sphear)

Answer 38

4/3 x π x r3

Question 39

unit for volume =

Answer 39

m3

Question 40

unit for density

Answer 40

kgm-3

Question 41

density equation

Answer 41

density = m divided by v (m=kg, v= m-3)

Question 42

laminar flow

Answer 42

streamlines that move in straight lines (or curved but e=with a constant distance between) and do not cross each other

Question 43

turbulent flow

Answer 43

streamlines that do cross each other and create vortices and eddy current.

Question 44

what is drag?

Answer 44

objects that experience lots of turbulant flow, experience drag e.g a tractor experiences more drag than a racing car.

Question 45

how can objects be designed to experience less drag?

Answer 45

they can be designed to be more streamline e.g flat, sleek curves

Question 46

streamlined objects are more...

Answer 46

aerodynamic and are able to move quicker because they experience less drag

Question 47

what is viscosity

Answer 47

viscosity is a quantity that describes a fluids resistant flow

Question 48

a viscous fluid =

Answer 48

thicker less flowing fluid e.g honey

Question 49

is water viscus ?

Answer 49

no

Question 50

if you heat up a gas the viscosity will...

Answer 50

increase

Question 51

if you heat up a liquid the viscosity will...

Answer 51

decrease

Question 52

on a bike chain what kind of lubrixate should be used ?

Answer 52

a very viscous lubricate should be used e.g oil (wd40) .. as this is very viscous it will create a barrier between the chain and the cog so they do not catch on each other and cause any damage.

Question 53

definition of elastic

Answer 53

an object that will return to its original position once these stretching/ compressing forces have been removed.

Question 54

definition of inelastic

Answer 54

an object that will not return to its original position once stretching/ compressing forces have been removed

Question 55

(stress strain curves) | strong objects, their elastic limit will be...

Answer 55

at a higher stress (higher up the graph)

Question 56

(stress strain curves) | brittle objects break under very little strain , very little plastic deformation so their breaking point will be ...

Answer 56

not very far across the graph

Question 57

ductile objects experience alot of plastic deformation , they break under alot of strain so their breaking point will be ...

Answer 57

very far across the graph