materials

Question 1

stiff

Answer 1

high ym - strong because it can take a lot of stress fir little strain

Question 2

brittle

Answer 2

no plastic region

Question 3

tough

Answer 3

it permantely deforms to withstand stress

Question 4

ductile

Answer 4

lots of strain for little stress - does not need a lot of force

Question 5

hookes law

Answer 5

the force needed to stretch a string is directly proportional to the extension of the string

Question 6

what is k and what does it mean if it is high

Answer 6

spring constant and stiffer spring

Question 7

series (effective spring constant)

Answer 7

k = (1/k + 1/k)^-1 (like parallel resistors)

Question 8

in series do both springs feel each mass equally

Answer 8

yes

Question 9

overall spring constant (series)

Answer 9

less than each k in each spring (multiply by both extension)

Question 10

parallel (effective spring constant)

Answer 10

k = k1 + k2

Question 11

in parallel do both springs feel each mass equally

Answer 11

no, the weight is shared by the 2 sprigs

Question 12

overall spring constant (parallel)

Answer 12

overall k is bigger than k in each spring (multiple by 1 extension)

Question 13

hysterisis

Answer 13

-the energy stored in loading is greater than the energy released in unloading
-permanently plastically deforms bonds in the material
-goes back to og length and shape
-eg) rubber

Question 14

compressive forces

Answer 14

squeeze and object and reduce its size

Question 15

tensile forces

Answer 15

act to pull or stretch an object

Question 16

stiff

Answer 16

resists deformation
ceramic

Question 17

tough

Answer 17

resists breaking, even after deforming
aluminum

Question 18

strong

Answer 18

resists deformation and breaking
steel

Question 19

ductile

Answer 19

deforms before it breaks
gold

Question 20

brittle

Answer 20

breaks before it deforms
glass

Question 21

hard

Answer 21

resists dents, scratches and other permanent changes under compressive forces
iron

Question 22

elastic

Answer 22

deforms but returns to og state

Question 23

plastic

Answer 23

does not return to og state

Question 24

what happens if you keep stretching an elastic material

Answer 24

the bonds between the atoms are stretched and when this breaks, it has reached its yield point

Question 25

limit of proportionality

Answer 25

in this region the extension is proportional to the force applied

Question 26

elastic limit

Answer 26

up until this point, the material will return to its initial shape/size when the force is removed

Question 27

yield point (just before a peak on graph)

Answer 27

-when the load is increased beyond this point, the material behaves plastically
- a small increase in load causes a very large increase in extension and the material remains extended once the fore has been removed

Question 28

breaking point

Answer 28

the load will break the material

Question 29

stress

Answer 29

how much force is affecting the cross sectional area

Question 30

strain

Answer 30

ratio between extension and og length

Question 31

what should you do if strain is in a percentage

Answer 31

make it into a fraction

Question 32

if a material is stiff, what does this mean about the strain and ym

Answer 32

smaller the strain = bigger the ym

Question 33

what do you compare using the gradient of a stress- strain graph

Answer 33

stiffness