Deck 17: Engineering Materials

Question 1

Plastics are often classified into two categories:

A)foams and vinyls
B)thermoplastics and thermosets
C)flexible and rigid
D)transparent and opaque

Answer 1

B

Question 2

Steel is an alloy of iron with approximately

Answer 2

A

Question 3

Timber is commonly classified as

A)softwood
B)hardwood
C)medium density fiber
D)softwood and hardwood

Answer 3

D

Question 4

In general, under axial loading (when pulled), wood is stronger in a direction parallel to the
grain than it is in a direction across the grain.

Question 5

Precast concrete slabs, blocks, and structural members are fabricated in less time with less
cost in factory settings where surrounding conditions are controlled.

Question 6

Wood is stronger in a direction normal to the grain when it is bent.

Question 7

In general, the higher the density of wood the lower the strength.

Question 8

In general the properties of materials may be divided into three groups.

A)electrical, mechanical, thermal
B)viscosity, density, temperature
C)resilience, toughness, heat capacity
D)none of the above

Question 9

The strength to weight ratio is defined as

A)the ratio of the strength of the material to its weight
B)the ratio of the strength of the material to its specific weight
C)the ratio of the strength of the material to its mass
D)the ratio of the strength of the material to its modulus of elasticity

Question 10

Polymers are the backbone of what we call plastics.

Question 11

Cast iron is considered a ductile material.

Question 12

When copper is alloyed with zinc it is commonly called

A)brass
B)bronze
C)aluminum bronze
D)zinc-copper

Question 13

Which of the following materials are considered lightweight metals?

A)Aluminum
B)Titanium
C)Magnesium
D)All of the above

Question 14

Concrete is commonly reinforced with steel bars or steel mesh to

A)increase its rigidity
B)increase its weight
C)increase its load bearing capacity
D)none of the above

Question 15

Concrete is stronger in tension than it is in compression.

Question 16

Steel is approximately

A)two times stiffer than aluminum alloys
B)four times stiffer than aluminum alloys
C)three times stiffer than aluminum alloys
D)ten times stiffer than aluminum alloys

Question 17

Modulus of elasticity is a measure of how easily a material will stretch when pulled or how
well the material will shorten when pushed.

Question 18

The value of electrical resistivity is a measure the resistance of material to the flow of
electricity.

Question 19

Alcohol has a lower vapor pressure value than water.

Question 20

Concrete is stronger in tension than it is in compression.

Question 21

There are two common ways of expressing the amount of water vapor in air:

A)dew point and relative humidity.
B)dew point and absolute humidity.
C)absolute humidity and relative humidity.
D)none of the above

Question 22

Air and water are among the most abundant fluids on earth.

Question 23

Silicon is a nonmetallic chemical element that is used in the manufacture of transistors and
electronic computer chips.

Question 24

The term fluids refers to liquids, not gases.

Question 25

The ratio of the amount of moisture in the air to the maximum amount of moisture that air can hold is known as

A)dew point.
B)absolute humidity.
C)relative humidity.
D)none of the above

Question 26

Which type of glass has the higher coefficient of thermal expansion?

A)Ordinary glass
B)Silica glass

Question 27

Composites are created by combing two or more solid materials to make a new material that
has properties that are superior to those of the individual components.

Question 28

Silicone is a synthetic compound that is commonly used in lubricants, varnishes, and
waterproofing products.

Question 29

The most widely used form of glass is soda-lime-silica glass.

Question 30

Metallic oxides are added to give glass various colors.

Question 31

Composites may be classified into

A)polymer-matrix composites
B)metal-matrix composites
C)ceramic-matrix composites
D)all of above

Question 32

Examples of fibers used in the construction of composite materials include

A)glass
B)graphite
C)silicon carbide fibers
D)all of above

Question 33

The ratio of the mass of water vapor to the mass of dry air is known as

A)dew point.
B)absolute humidity.
C)relative humidity.
D)none of the above

Question 34

Most of the ultraviolet radiation arriving on earth from the sun is absorbed by

A)air.
B)nitrogen.
C)water vapor.
D)ozone.

Question 35

Which type of glass is better in high-temperature applications?

A)Ordinary glass
B)Silica glass

Question 36

Air is often used

A)as a cooling and heating medium.
B)in controlling thermal comfort in buildings.
C)as a controlling medium to turn equipment on and off.
D)to drive power tools.
E)all of the above

Question 37

The earth's atmosphere, which we refer to as air, is a mixture of approximately

Question 38

Most people feel comfortable when the relative humidity is around

Question 39

Fiber optics is the branch of science that deals with transmitting data, voice, and images
through thin plastic or glass fibers.

Question 40

Composite materials consist of two main ingredients: matrix material and fibers.

Question 41

Mechanical engineers need to understand the thermophysical properties of liquid water and
steam when designing power plants.

Question 42

The higher the air temperature , the less water vapor the air can hold before it is fully
saturated.

Question 43

Approximately what fraction of the earth's surface is covered with water?

Question 44

Understanding the properties of liquid water and steam is important to which engineering discipline?

A)Mechanical engineering
B)Civil engineering
C)Manufacturing engineering
D)All of the above

Question 45

Water is a common engineering material.

Question 46

Water is used as a cutting tool to cut stone and steel.

Question 47

Groundwater refers to water that has collected on the ground.

Question 48

Surface water refers to water in reservoirs, lakes, rivers, and streams.