Unit 1 (A1 Properties of Materials)

Question 1

What is the definition of Mass?

Answer 1

Measure of how much matter there is within an object

Mass is not affected by gravity.

Question 2

What is the definition of Density?

Answer 2

The amount of Mass in an object per a certain amount of volume.

Water has a density of 1000kg per meter cubed. (Kg/m³)

Question 3

What is Strength/Stress?

Answer 3

The force per unit area

Question 4

What is the formula for calculating Strength/Stress?

Answer 4

Stress = Force / Cross sectional area (N/m²)

Pascals

Question 5

What are the SI units for Density?

Answer 5

(Kg/m³)

Question 6

What are the SI units for Strength/Stress?

Answer 6

Pascals.

N/m²

Question 7

What is the definition for compressive strength?

Answer 7

The maximum compressive load an object can bear prior to failure, divided by its cross sectional area.

Question 8

Name a material with good compressive strength

Answer 8

1. Concrete

2. Ceramics

Question 9

What is the definition of tensile strength?

Answer 9

The maximum tensile load an object can withstand before failure, divided by its cross sectional area.

Question 10

Name a material with good tensile strength

Answer 10

Glass
Kevlar
Carbon fibre

Question 11

What is the definition of shear strength?

Answer 11

The maximum shear load an object can withstand before failure, divided by its cross sectional area.

Question 12

What is the definition of bending strength?

Answer 12

The ability to resist deformation under load.

Question 13

What is the definition of hardness?

Answer 13

Ability of a material to resist deformation, which is determined by a standard test where the surface resistance to indentation is measured.

Question 14

What is the definition of toughness?

Answer 14

The ability of a material to absorb energy without fracturing.

Question 15

What is the definition of malleability

Answer 15

The property of a metal to deform under compression and take on a new shape

Question 16

Give and example of a malleable metal

Answer 16

1. Gold
2. Silver
3. Aluminium
4. Copper

Question 17

What is the definition of workability?

Answer 17

Ease of placement

Question 18

What is the definition of stiffness

Answer 18

resistance to elastic deformation when a load is applied.

Question 19

What is the definition of fatigue ?

Answer 19

Where structures fail when subjected to a cyclic load. Cyclic load is when loads are applied, removed and then re-applied

Question 20

What is the definition of creep?

Answer 20

The tendency of a solid material to move slowly or deform permanently under the influence of persistent mechanical stresses

Question 21

What is the definition of fire resistance ?

Answer 21

The property of materials that prevents or retards the passage of excessive heat, hot gasses or flames

Quantified by fire resistance rating

Question 22

What is the definition of electrical conductivity ?

Answer 22

The measure of how easily electricity flows through a material

Question 23

Give an example of a material that has high electrical conductivity

Answer 23

Copper
Aluminium
Gold
Silver

Question 24

What is the definition of thermal conductivity ?

Answer 24

(often denoted by k or λ)

Refers to the ability of a material to transfer or conduct heat.

Thermal conductivity occurs through molecular agitation.

Heat moves along a temperature gradient, from an area of high temperature and high molecular energy to an area with a lower temperature and lower molecular energy.

This transfer will continue until thermal equilibrium is reached.

Question 25

Give an examples of materials with high and low thermal conductivity

Answer 25

High:
Metals such as Copper, Aluminium, Brass

Low:
Wood
Rubber

Question 26

Resistance to Moisture Penetration

Answer 26

Rain, particularly when driven by strong winds, can penetrate the thickest masonry walling, typically at mortar joints, through stones and defective or dirty wall ties.

Damaged or blocked gutters and downpipes, provide another source of penetrating moisture

Moisture may penetrate a wall by absorption of water from the ground that is in contact with foundation walls or through rain falling on the wall.

Question 27

Resistance to Vapour Penetration

Answer 27

Water vapour spreads more easily inside structures, when a gradient of pressure and temperature is established between the sides of the material

The water vapour modifies the behaviour of the insulator, increasing the thermal conductivity value and thus increasing the energy losses and the risk of condensations.

By their nature, all materials, except glass and metals, are permeable to water vapour.

A good insulator must avoid the penetration of water vapour.

Question 28

Resistance to Degradation

Answer 28

Allbuilding materialscan suffer from deterioration and decay if they are not protected and maintained correctly.

Commonreasons for thedegradation of construction materialsinclude:- Naturalagents, Moisture, Shrinkage, Exposureconditions, Corrosioninmetals, Loading and Chemical.

Question 29

Embedded Energy

Answer 29

Embodied energyis the sum of all theenergyrequired to produce any goods or services, considered as if that energy was incorporated or ‘embodied’ in the product itself.

The concept can be useful in determining the effectiveness of energy-producing orenergy savingdevices, or the “real” replacement cost of a building, and, because energy-inputs usually entailgreenhouse gasemissions, in deciding whether a product contributes to or mitigatesglobal warming.

Question 30

Recycling Potential

Answer 30

Recyclingis the process of converting waste materials into new materials and objects.

Recyclingcan prevent the waste ofpotentiallyuseful materials and reduce the consumption of fresh raw materials, thereby reducing: energy usage, air pollution (from incineration), and water pollution (from landfilling).