Materials

Question 1

Density

Answer 1

A measure of the compactness of a substance
p = m/v

Question 2

Hookes law equation

Answer 2

F = k △L
F = force in newtons
k = the stiffness or spring constant in Nm
△L = extension in meters

Question 3

Elastic limit

Answer 3

If you increase the force past the elastic limit, the material will be permanently stretched
Where all forces are removed, the material will be longer than at the start

Question 4

Limit of proportionality

Answer 4

The points beyond which all force is no longer proportional to extension
Also known as hooke law limit

Question 5

Tensile stress

Answer 5

Defined as the force applied
Stress = F/A
Four divided by cross-sectional area
Unit of stress is pascals or Nm^-2

Question 6

Tensile strain

Answer 6

Defined as the change in length, I.e. the extension divided by the original length of the material
Strain = ΔL / L

Question 7

Breaking stress

Answer 7

Distress that is big enough to break a material

Question 8

Ultimate tensile stress

Answer 8

This is the maximum stress that the material can withstand

Question 9

Work done equation

Answer 9

Work done = 0.5F x ΔL

Question 10

Elastic train energy equation

Answer 10

E = 0.5F ΔL

E = 0.5k (ΔL)^2

Question 11

Young modulus

Answer 11

E= tensile stress/tensile strain

Question 12

Yield point

Answer 12

Hear the material suddenly starts to stretch without any extra loads