Exam 3

Question 1

A tire stops a car by use of friction. What modulus should we use to calculate the stress and strain on the tire? 
compression modulus 
Young's modulus 
bulk modulus 
shear modulus

Answer 1

shear modulus

Question 2

As ice floats in water, about 10% of the ice floats above the surface of the water. If we float some ice in a glass of water, what will happen to the water level as the ice melts?

The water level will become lower.
The water level will rise 10% of the volume of the ice that melts.
The water level will remain unchanged.
The water level will rise, but not as much as the 10%.

Answer 2

The water level will remain unchanged.

Question 3

A large stone is resting on the bottom of the swimming pool. The normal force of the bottom of the pool on the stone is equal to the:

weight of the stone.
weight of the water displaced.
difference between the weight of the stone and the weight of the displaced water.
sum of the weight of the stone and the weight of the displaced water.

Answer 3

difference between the weight of the stone and the weight of the displaced water.

Question 4

A heavily loaded boat is floating in a pond. The boat sinks because of a leak. What happens to the surface level of the pond?

More information is needed to reach a conclusion.
It goes down.
It goes up.
It stays the same.

Answer 4

It goes down.

Question 5

A heavily loaded boat is floating in a pond. The boat starts to sink because of a leak but quick action plugging the leak stops the boat from going under although it is now deeper in the water. What happens to the surface level of the pond?

It goes up.
It goes down.
More information is needed to reach a conclusion.
It stays the same.

Answer 5

It stays the same.

Question 6

A container is filled with water and the pressure at the bottom of the container is P. Then the container is emptied halfway and topped off with oil of density 0.80·103 kg/m3, which floats on top of the water. What is the pressure at the bottom of the container now?
a pressure < P
the same pressure P
This is unable to be determined with the information given.
a pressure > P

Answer 6

a pressure < P

Question 7

When an artery gets a constricted region due to plaque, how does the pressure in this region compare to the pressure in an unconstricted region adjacent?

Since this is a closed system, the pressure is the same in both regions.
In the constricted region the blood moves at a lower speed than in the unconstricted region resulting in an increased pressure.
In the constricted region the blood moves at a higher speed than in the unconstricted region resulting in a decreased pressure.
In the constricted region the blood moves at a higher speed than in the unconstricted region resulting in an increased pressure.

Answer 7

In the constricted region the blood moves at a higher speed than in the unconstricted region resulting in a decreased pressure.

***Think of hypotension in patients with a stroke

Question 8

An ice cube with a small solid steel sphere frozen inside floats in a glass of water filled to the brim. What happens to the level of water in the glass as a result of the ice melting?

It goes up, overflowing.
It depends on air pressure, thus the answer is indeterminate.
It stays the same.
It goes down.

Answer 8

It goes down.

Question 9

Which best describes the relationship between two systems in thermal equilibrium? 
masses are equal 
volumes are equal 
zero velocity 
no net energy is exchanged

Answer 9

no net energy is exchanged

Question 10

The thermal expansion of a solid is caused by:

the breaking of bonds between atoms.
increasing the distance between equilibrium positions for the vibrating atoms.
increasing the amplitude of the atoms vibration.
all of the above.

Answer 10

increasing the distance between equilibrium positions for the vibrating atoms.

Question 11

A steel plate has a hole drilled through it. The plate is put into a furnace and heated. What happens to the size of the inside diameter of a hole as its temperature increases?

remains constant
becomes elliptical
increases
decreases

Answer 11

increases

Question 12

The coefficient of area expansion is:

half the coefficient of volume expansion.
triple the coefficient of linear expansion.
three halves the coefficient of volume expansion.
double the coefficient of linear expansion.

Answer 12

double the coefficient of linear expansion.

Question 13

What happens to its moment of inertia when a steel disk is heated?

It increases for half the temperature increase and then decreases for the rest of the temperature increase.
It increases.
It stays the same.
It decreases.

Answer 13

it increases
**inertia is the property to stay the same and remained unchanged, so if it is being heated its inertia will increase in order for the disk to stay the same

Question 14

Two one-liter containers each contain 10 moles of a gas. The temperature is the same in both containers. Container A holds helium (molecular mass = 4 u), and Container B holds oxygen (molecular mass = 16 u). Which container has the higher pressure and by what factor?

Both containers have the same pressure.
Container A has 4 times the pressure of Container B.
Container A has 2 times the pressure of Container B.
This is foil Five, and it is currently set to “false.”

Answer 14

Both containers have the same pressure.

Question 15

The absolute temperature of an ideal gas is directly proportional to which of the following properties, when taken as an average, of the molecules of that gas?

speed
mass
kinetic energy
momentum

Answer 15

kinetic energy

Question 16

If the temperature of an ideal gas contained in a box is increased:

the distance between molecules in the box will be increased.
the average speed of the molecules in the box will be increased.
the average velocity of the molecules in the box will be increased.
all of the above.

Answer 16

the average speed of the molecules in the box will be increased.

Question 17

For an ideal gas of a given mass, if the pressure remains the same and the volume increases:

the average kinetic energy of the molecules increases.
Nothing can be determined about the molecular kinetic energy.
the average kinetic energy of the molecules stays the same.
the average kinetic energy of the molecules decreases.

Answer 17

the average kinetic energy of the molecules increases.

Question 18

John rapidly pulls a plunger out of a cylinder. As the plunger moves away, the gas molecules bouncing elastically off the plunger are:

rebounding at the same speed as they would have if the plunger weren’t removed.
Whether they speed up or slow down depends on how fast the plunger is removed.
rebounding at a lower speed than they would have if the plunger weren’t removed.
rebounding at a higher speed than they would have if the plunger weren’t removed.

Answer 18

rebounding at a lower speed than they would have if the plunger weren’t removed.

Question 19

Consider two containers with the same volume and temperature. Container One holds “dry” air–a mixture of nitrogen and oxygen. Container Two holds “moist” air. The “moist” air has the same ratio of nitrogen to oxygen molecules, but also contains water vapor. According to the ideal gas law, if the pressures are equal, the weight of the gas in Container One will be:

heavier than the gas inside the second container.
equal to the weight of the gas in the second container.
lighter than the gas inside the second container.
all the above are incorrect because the pressures cannot be equal.

Answer 19

heavier than the gas inside the second container.

Question 20

Evaporation cools the liquid that is left behind because the molecules that leave the liquid during evaporation:

have greater than average speed.
have kinetic energy.
have broken the bonds that held them in the liquid.
create vapor pressure.

Answer 20

have greater than average speed.

Question 21

A quantity of a monatomic ideal gas expands to twice the volume while maintaining the same pressure. If the internal energy of the gas were U0 before the expansion, what is it after the expansion?

2 U0
The change in temperature must also be known to answer this question.
4 U0
U0

Answer 21

2 U0

Question 22

Metal lids on glass jars can often be loosened by running them under hot water. Why is this?

The hot water is a lubricant.
The metal has a higher coefficient of thermal expansion than glass so the metal expands more than the glass thus loosening the connection.
The metal and glass expand due to the heating, and the glass being of smaller radius expands less than the metal.
This is just folklore.

Answer 22

The metal has a higher coefficient of thermal expansion than glass so the metal expands more than the glass thus loosening the connection.

Question 23

Why do vapor bubbles get larger in boiling water as they approach the surface?

Bubbles always get bigger after they form.
They only appear to get larger, this being a magnification effect due to looking through the water.
The bubbles’ pressure increases as they rise.
The pressure in the water decreases as the bubble moves toward the surface.

Answer 23

The pressure in the water decreases as the bubble moves toward the surface.

Question 24

Suppose the pressure of 20 g of an ideal monatomic gas is tripled while its volume is halved. What happens to the internal energy of the gas?

It stays the same, as the described changes do not involve internal energy.
It increases.
This depends on the molecular weight of the gas involved, thus this is indeterminate.
It decreases.

Answer 24

It increases.

Question 25

The temperature of a quantity of ideal gas in a sealed container is increased from 0°C to 273°C. What happens to the rms speed of the molecules of the gas as a result of this temperature increase? It increases but it less than doubles It doubles. It does not change since rms speed is independent of temperature. It quadruples.

Answer 25

It increases but it less than doubles

Question 26

The noble gases, listed by increasing molecular weight, are He, Ne, Ar, Kr, Xe, and Rn. If samples of 1 mole each of these gases are placed in separate containers and heated to 300 K, which gas has the greatest internal energy and the molecules of which gas have the highest rms speed? The Rn has the greatest internal energy, and the He has the greatest rms speed. All the gases have the same internal energy, and the He has the greatest rms speed. All the gases have the same internal energy, and the Rn has the greatest rms speed. The He has the greatest internal energy, and the Rn has the greatest rms speed.

Answer 26

All the gases have the same internal energy, and the He has the greatest rms speed.

Question 27

``` Sea breezes that occur near the shore are attributed to a difference between land and water with respect to what property? coefficient of volume expansion specific heat mass density emissivity ```

Answer 27

specific heat

Question 28

``` On a sunny day at the beach, the reason the sand gets so hot and the water stays relatively cool is attributed to the difference in which property between water and sand? thermal conductivity specific heat mass density temperature ```

Answer 28

specific heat

Question 29

As I use sandpaper on some rusty metal, the sandpaper gets hot because: heat is flowing from the metal into the sandpaper. heat is flowing from my hand into the sandpaper. frictional processes increase the internal energy of the sandpaper. heat is flowing from the sandpaper into the metal.

Answer 29

frictional processes increase the internal energy of the sandpaper.

Question 30

Heat flow occurs between two bodies in thermal contact when they differ in what property? specific heat temperature density mass

Answer 30

temperature

Question 31

Twenty grams of a solid at 70°C is place in 100 grams of a fluid at 20°C. Thermal equilibrium is reached at 30°C. The specific heat of the solid: is more than that of the fluid. cannot be compared to that of a material in a different phase. is less than that of the fluid. is equal to that of the fluid.

Answer 31

is more than that of the fluid.

Question 32

Which of the following best describes a substance in which the temperature remains constant while at the same time it is experiencing an inward heat flow? gas substance undergoing a change of state liquid solid

Answer 32

substance undergoing a change of state

Question 33

If one's hands are being warmed by holding them to one side of a flame, the predominant form of heat transfer is what process? vaporization radiation conduction convection

Answer 33

radiation

Question 34

When a wool blanket is used to keep warm, what is the primary insulating material? a thin layer of aluminum foil (usually not apparent) inside the blanket air the trim around the edge of the blanket wool

Answer 34

air

Question 35

If heat is flowing from a table to a block of ice moving across the table, which of the following must be true? The table is rough and there is friction between the table and ice. The ice is cooler than the table. The ice is changing phase. All three are possible, but none is absolutely necessary.

Answer 35

The ice is cooler than the table. ****Think about homeostasis

Question 36

Inside a house, stepping on a tile floor barefooted may feel almost cold, but stepping on carpet in an adjacent room feels comfortably warm. Why is this? It's because the thermal conductivity of tile is less than that of carpet. It's because the thermal conductivity of carpet is less than that of tile. It's because the tile is below room tempera-ture while the carpet is at room temperature. It's because the tile is at room temperature while carpet is normally warmer.

Answer 36

It's because the thermal conductivity of carpet is less than that of tile.

Question 37

According to the first law of thermodynamics, the sum of the heat gained by a system and the work done on that same system is equivalent to which of the following? entropy change internal energy change temperature change specific heat

Answer 37

internal energy change

Question 38

If an ideal gas does positive work on its surroundings, we may assume, with regard to the gas: volume increases. internal energy decreases. temperature increases. pressure increases.

Answer 38

volume increases

Question 39

In an isovolumetric process by an ideal gas, the system's heat gain is equivalent to a change in: pressure. temperature. internal energy. volume.

Answer 39

internal energy.

Question 40

An adiabatic expansion refers to the fact that: the pressure remains constant. the volume remains constant. the temperature remains constant. no heat is transferred between a system and its surroundings.

Answer 40

no heat is transferred between a system and its surroundings.

Question 41

During an isobaric process which one of the following does not change? internal energy temperature volume pressure

Answer 41

pressure

Question 42

Area on a P-V diagram has units associated with: momentum. energy. temperature. change in temperature.

Answer 42

energy

Question 43

On a P-V diagram, an ____ process is represented by a horizontal line. isothermal adiabatic isovolumetric isobaric

Answer 43

isobaric

Question 44

In an isothermal process for an ideal gas system (where the internal energy doesn't change), which of the following choices best corresponds to the value of the work done on the system? its heat intake twice its heat intake the negative of its heat intake twice the negative of its heat intake

Answer 44

the negative of its heat intake

Question 45

Consider three drinking glasses. All three have the same area base, and all three are filled to the same depth with water. Glass A is cylindrical. Glass B is wider at the top than the bottom, and so holds more water than A. Glass C is narrower at the top than the bottom, and so it holds less water than A. Which glass has the greatest liquid pressure? - Glass A - Glass B - Glass C - All three have equal pressure

Answer 45

All three have equal pressure **Pressure is dependent on area, so if all three glasses have the same area, they will all have the same liquid pressure

Question 46

You are originally 1.0m beneath the surface of a pool. If you dive to 2.0m beneath the surface, what happens to the absolute pressure on you? - it more than doubles - it less than doubles - it doubles - it quadruples

Answer 46

it less than doubles ``` **pressure on you = Patm + ρgh if h=1 pressure =Patm + ρg if h=2 pressure =Patm + 2ρg ```

Question 47

50cm^3 of wood is floating on water, and 50cm^3 of iron is totally submerged. Which has the greater buoyancy force on it? - the iron - the wood - Both have same buoyant force - Cannot be determined without their densities

Answer 47

Iron ** buoyant force = rho * g * V iron has more V submerged therefore has more buoyancy force.

Question 48

``` A steel ball sinks in water but floats in a pool of Mercury. Where is the buoyant force on the ball greater? -Submerged in water -Floating on the Hg -It is the same in both cases Cannot be determined ```

Answer 48

floating on Mercury **If the ball floats in a pool of liquid, then the amount of liquid displaced by the ball is equivalent to the buoyant force exerted by the liquid to the ball... Since the steel ball sinks in water, it means that there is not enough buoyant force exerted by water to the ball to let it float... Therefore, since the ball floats in a pool of mercury, it means that there is more buoyant force exerted by mercury on the steel ball...In this case the buoyant force exerted by the liquid mercury is equivalent to the weight of the steel ball.

Question 49

Salt water is more dense than fresh water. A ship floats in both fresh water and salt water. Compared to the fresh water, the volume of water displaced in the salt water is - more - the same - less - cannot be determined

Answer 49

Less **Because the salt water is denser, the ship floats higher, therefore displaces less water.