Module 3 - 3.4.2 Mechanical Properties of Matter

Question 1

When work is done on a wire to stretch/compress it

Answer 1

the wire itself stores elastic potential energy

Question 2

Tensile Stress

Answer 2

The force applied per unit cross sectional area

Question 3

Tensile Strain

Answer 3

The fractional change in length under load

Question 4

Young’s Modulus

Answer 4

• the gradient of a stress-strain graph
• stiffer materials have a higher Young’s Modulus

Question 5

Ductile

Answer 5

The material can be drawn into wires
- will show plastic deformation under tensile stress before breaking

Question 6

Malleable

Answer 6

The material can be hammered into flat sheets
- will show extensive plastic deformation when subjected to compressive forces

Question 7

Brittle

Answer 7

The material will break with little or no plastic deformation

Question 8

Hard

Answer 8

The material will resist plastic deformation by surface indentation or scratching

Question 9

Polymeric

Answer 9

The material is made of long chains of molecules called polymers

Question 10

The Ultimate Tensile Strength of a Material

Answer 10

The maximum stress it can withstand while being pulled or stretched before it fails or breaks

Question 11

Polymer Stress-Strain Graph:
- the area under the loading curve is
- the area under the unloading curve is
- the area between the loading and unloading curve is called

Answer 11

• the work done in stretching
• the energy recovered when unloading
• the hysteresis loop