Booklet 1: Matter and Materials

Question 1

Hooke’s Law

Answer 1

the extension of an elastic body is directly proportional to the force applied to it as long as the elastic limit is not exceeded.

Question 2

Elastic Potential Energy

Answer 2

energy stored as a result of applying a force to deform an elastic object.

Question 3

Stress

Answer 3

force applied per unit cross sectional area of the wire

Question 4

Strain

Answer 4

the fractional increase in the original length of the wire

sometimes given as %

Question 5

Young’s Modulus/The Young Modulus

Answer 5

a measure of stiffness of a material independent of shape and size of a substance. It is the ratio of tensile stress against tensile strain, within limit of proportionality.

Question 6

Brittle

Answer 6

no plastic deformation/only elastic deformation, obeys Hooke’s Law, σ ∝ ε, break if too much load
eg. glass, cast iron

Question 7

Ductile

Answer 7

deform elastically until elastic limit is reached, then deforms plastically until the UTS (Ultimate Tensile Strength) is reached, where it breaks
eg. copper, gold

Question 8

Polymeric

Answer 8

long chain polymers, extremely flexible, high strain before snapping (long x-axis)
eg. polythene