Question 1

The specific gravity of a material is the ratio of its density relative to the density of water:

Accepted Answer

Specific gravity is indeed defined as the ratio of the density of a material to the density of water at a specified temperature, typically 4°C, where water has its maximum density.

Question 2

The strength-to-weight ratio of a material is its yield strength divided by its density:

Accepted Answer

the ratio is based on tensile strength, not yield strength.

Question 3

The coefficient of thermal expansion measures the change in volume of a material per degree of temperature:

Accepted Answer

the coefficient of thermal expansion measures the change in length, not volume, per degree of temperature.

Question 4

The thermal expansion properties of polymers are generally&#10;A)greater than&#10;B)less than&#10;C)the same as those of metals

Accepted Answer

Polymers typically have greater thermal expansion properties than metals due to their molecular structure, which allows for more movement and expansion when heated.

Question 5

In the heating of most metal alloys, melting begins at a certain temperature and concludes at a higher temperature.In these cases, which of the following temperatures marks the beginning of melting:&#10;A)liquidus&#10;B)solidus

Accepted Answer

The solidus temperature marks the beginning of melting for most metal alloys. It is the temperature at which the alloy starts to melt or the first liquid phase starts to appear from the solid.

Question 6

Volumetric specific heat is best defined by which one of the following:&#10;A)capability of a material to transfer heat through itself&#10;B)density divided by specific heat&#10;C)specific heat divided by density&#10;D)specific heat multiplied by density

Accepted Answer

Volumetric specific heat is defined as the specific heat capacity of a material multiplied by its density. This gives a measure of the amount of heat per unit volume a material can store.

Question 7

The thermal diffusivity of a material is its thermal conductivity divided by its specific heat:

Accepted Answer

thermal diffusivity is a material's thermal conductivity divided by its volumetric specific heat, not weight specific heat.

Question 8

Copper is generally considered easy to weld because of its high thermal conductivity:

Accepted Answer

the high thermal conductivity of copper makes it difficult to weld because the heat flows away from the joint rather than being concentrated to permit melting of the metal.

Question 9

The mass diffusion rate dm/dt across a boundary between two different metals is a function of which of the following variables (four best answers):&#10;A)concentration gradient dc/dx&#10;B)contact area&#10;C)density&#10;D)melting point&#10;E)thermal expansion&#10;F)temperature&#10;G)time

Accepted Answer

Answers (a) and (b) are included in Equation (4.5).Temperature (f) has a strong influence on the diffusion coefficient.Time (g) figures into the process because it affects the concentration gradient; as time elapses, the concentration gradient is reduced so that the rate of diffusion is reduced.

Question 10

Ohm's Law is expressed by which one of the following relationships:&#10;A)current = voltage divided by resistivity&#10;B)current = voltage multiplied by resistance&#10;C)power = current multiplied by voltage&#10;D)resistance = voltage multiplied by current&#10;E)voltage = current multiplied by resistance

Accepted Answer

This relationship is equivalent to Equation (4.6) in the text, which states that current = voltage divided by resistance.

Question 11

The electrical conductivity of a material is the reciprocal of its resistivity:

Accepted Answer

The answer of The electrical conductivity of a material is...

Question 12

A superconductor is characterized by which one of the following:&#10;A)high conductivity&#10;B)resistivity properties between those of conductors and semiconductors&#10;C)very low resistivity&#10;D)zero resistivity

Accepted Answer

The answer of A superconductor is characterized by which one...

Question 13

In an electrolytic cell, the anode is the electrode that is&#10;A)positive&#10;B)negative.

Accepted Answer

The answer of In an electrolytic cell, the anode is...

Deck 4: Physical Properties of Materials