Materials

Question 1

Find force on an object (using hooke’s law)

Answer 1

force = force constant*extension
(F = kx)

Question 2

Spring constant of springs in series

Answer 2

1/kt = 1/k1 + 1/k2 + …

Question 3

Spring constant of springs in parallel

Answer 3

kt = k1 + k2 + …

Question 4

Hooke’s law

Answer 4

Force is proportional to extension up to the limit of proportionality

Question 5

Find tensile stress

Answer 5

Stress = force/cross sectional area
(σ = F/A)

Question 6

Find tensile strain

Answer 6

Strain = extension/original length
(ε = x/L)

Question 7

Find young modulus

Answer 7

Young modulus = stress/strain
(E = σ/ε
or
E = FL/Ax)

Question 8

Ultimate tensile strength

Answer 8

Maximum stress reached before a material breaks (peak of a stress-strain graph)

Question 9

Young modulus

Answer 9

Stiffness of a material (gradient of a stress-strain graph)

Question 10

Toughness

Answer 10

Energy per unit volume needed to break a material (area under a stress-strain graph up to breaking point)

Question 11

Find elastic potential energy (using force constant)

Answer 11

Energy = 0.5*force constant*extension^2
(E = 0.5kx²)

Question 12

Find elastic potential energy (using force)

Answer 12

Energy = 0.5*force*extension
(E = 0.5Fx)

Question 13

Gradient of a force-extension graph

Answer 13

Force/extension = force constant

Question 14

Area under a force-extension graph

Answer 14

Force*extension = elastic potential energy

Question 15

Gradient of a stress-strain graph

Answer 15

Stress/strain = young modulus (stiffness at that point)

Question 16

Area under a stress-strain graph

Answer 16

Stress*strain = energy per unit volume (same unit as pressure)

Question 17

Elastic deformation

Answer 17

Deformation where the object returns to its original length

Question 18

Plastic deformation

Answer 18

Deformation where the object does not return to its original length