Materials

Question 1

Define the density of a material.

Answer 1

mass/volume

Question 2

State Hooke’s law

Answer 2

the force (needed to stretch a spring is directly) is proportional
to the extension
up to the limit of proportionallity

Question 3

Describe the behaviour of a wire that obeys Hooke’s law

Answer 3

the extension produced (by a force) in a wire is directly
proportional to the force applied
applies up to the limit of proportionality or elastic limit

Question 4

Explain what is meant by the elastic limit of the wire.

Answer 4

the maximum amount that a material can be
stretched (by a force) and still return to its original length
when the force is removed

Question 5

Define the Young modulus of a material and state the unit in which it is measured.

Answer 5

ratio of tensile stress to tensile strain (1)

unit: Pa

Question 6

Describe how to obtain, accurately by experiment, the data to determine the Young
modulus of a metal wire.
A space is provided for a labelled diagram

Answer 6

Quantities to be measured
• describe/show means of applying a load/force to a wire
• measure original length
• measure extension
• measure diameter
• extension = extension length ‘ original length (needed for six marks)
Measuring instruments
• use of rule/ruler/tape measure
• measure diameter with micrometer
• use of travelling microscope to measure extension, or extension
of wire measured with vernier scale for Searle’s apparatus
Accuracy
• varying load/mass
• repeat readings (of length or extension)

Question 7

tensile stress def

Answer 7

(stretching) force (applied) per unit

cross-sectional area

Question 8

tensile strain def

Answer 8

extension (produced) per unit length

Question 9

mass per unit length equation

Answer 9

density x area