materials

Question 1

equation for force (F) when stretching/compressing material? (x)

Answer 1

F = kx

where x = extension (for compression only difference is extension is negative)

Question 2

equation for energy (E) stored by material when stretching or compressing material? (F, x)

Answer 2

E = 0.5Fx

Question 3

equation for energy (E) stored by material when stretching or compressing material? (x)

Answer 3

E = 0.5k(x^2)

Question 4

equation for stress on material? (F, A)

Answer 4

σ = F/A

Question 5

equation for strain (ε) on material? (x, L)

Answer 5

ε = x/L

where x = extension and L = original length

Question 6

equation for young modulus (E)? (σ, ε)

Answer 6

E = stress/strain
or
E = σ/ε

(so E = gradient of stress-strain graph)

Question 7

equation for young modulus (E)? (F, L, A, x)

Answer 7

E = FL/Ax
(E = “flax”?)

Question 8

equation for density (ρ)? (m, v)

Answer 8

density = mass/volume
or
ρ = m/v

Question 9

equation for tensile strength? (F, A)

Answer 9

tensile strength = breaking force/cross-sectional area
OR
tensile strength = fracture F/A

(so from this you can realise that strength is measure of stress [that can be withstood by material])

Question 10

equation for fracture energy?

Answer 10

fracture energy = energy needed to fracture material/cross-sectional area

(can realise from this that fracture energy describes toughness of material)
(fracture energy can also be found by finding area under stress-strain graph up to breaking point)

Question 11

equation for charge carrier number density of material?

Answer 11

charge carrier number density = number of free charge carriers/volume

Question 12

equation for energy lost as heat by rubber due to elastic hysteresis?

Answer 12

energy lost = energy under force-extension graph of rubber when loading - energy under force-extension graph of rubber when unloading

energy lost = energy absorbed by rubber when loading - energy released by rubber when unloading