Physics Final

Front 1

The linear expansion of a material depends on which of the following?

Back 1

all of the above

Front 2

The temperature of an ideal gas increases.

Which of the following is true?

Back 2

The pressure, the volume, or both, may increase.

Front 3

An ideal gas is in a sealed rigid container. The average kinetic energy of the gas molecules depends most on

Back 3

the temperature of the gas.

Front 4

Diatomic oxygen has a molar mass 16 times that of diatomic hydrogen. The root-mean-square speed vrms for diatomic oxygen at 50∘C is:

Back 4

(14)(2000m/s)=500m/s

Front 5

The total translational kinetic energy of 1.0 mole of diatomic oxygen at 50∘C is:

Back 5

4000J

Front 6

When you put an ice cube in a glass of warm tea, which of the following happens?

Back 6

Heat flows from the tea into the ice cube.

Front 7

For objects at thermal equilibrium, which of the following is true?

Back 7

Each is at the same temperature

Front 8

As heat is added to water, is it possible for the temperature measured by a thermometer in the water to remain constant?

Back 8

Yes, the water could be changing phase.

Front 9

Radiation is emitted

Back 9

by any object not at 0 K.

Front 10

P=eσAT4, This formula applies to _______________.

Back 10

any object of total surface area A, Kelvin temperature T, and emissivity e

Front 11

What is the primary mode of energy transfer from hot coffee inside a Thermos bottle to the environment?

Back 11

radiation

Front 12

What is the primary mode of energy transfer from your bare feet to a cold ceramic bathroom floor in the middle of winter?

Back 12

conduction

Front 13

What is the primary mode of energy transfer from your body to your hands when you blow on them to warm them?

Back 13

convection

Front 14

What is the primary mode of energy transfer into your sealed car parked in the sun on a hot summer day?

Back 14

radiation

Front 15

What is the primary mode of the flow of energy from your tongue to a metal railing if you happen to lick it on a cold winter day?

Back 15

conduction

Front 16

If the old radiator is replaced with a new one that has longer tubes made of the same material and same thickness as those in the old unit, what should the total surface area available for heat exchange be in the new radiator to achieve the desired cooling temperature gradient?

Back 16

three-halves that of the old unit

Front 17

If the old radiator is replaced with a new one made of a material that has twice the thermal conductivity of the material of the old radiator, what should the total surface area available for heat exchange in the new radiator be to achieve the desired temperature gradient? Assume that the tubes of the new radiator are as thick as the tubes in the older unit.

Back 17

three-fourths that of the old unit

Front 18

In an isobaric compression of an ideal gas,

Back 18

work is done on the gas.

Front 19

Which is possible: converting (i) 100 J of work entirely into 100 J of heat, (ii) 100 J of heat entirely into 100 J of work?

Back 19

Both (i) and (ii) are possible

Front 20

An ideal gas undergoes an isothermal expansion from state A to state B. In this process

Back 20

Q>0,ΔU=0,W>0.

Front 21

Which physical law underlies the first law of thermodynamics?

Back 21

conservation of energy

Front 22

The quantity Q is the __________ that is added to the system.

Back 22

heat

Front 23

The quantity W in the first law refers to the __________.

Back 23

work done by the system

Front 24

What happens to the entropy of a bucket of water as it is cooled down (but not frozen)?

Back 24

It decreases.

Front 25

What happens to the entropy of a cube of ice as it is melted?

Back 25

It increases

Front 26

A heat engine operates between a high temperature of about 600∘C and a low temperature of about 300∘C. What is the maximum theoretical efficiency for this engine?

Back 26

≈34%.

Front 27

On a very hot day, could you cool your kitchen by leaving the refrigerator door open?

Back 27

No, the heat exhausted by the refrigerator into the room is more than the heat the refrigerator takes out of the room.

Front 28

Which of the following possibilities could increase the efficiency of a heat engine or an internal combustion engine?

Back 28

Increase the temperature of the hot part of the system and reduce the temperature of the exhaust.

Decrease the temperatures of both the hot part and the exhaust part of the system by the same amount.

Front 29

Which of the following statements are true?

Back 29

For the gas to do positive work, the cycle must be traversed in a clockwise manner.

The net work done by the gas is proportional to the area inside the closed curve.

Front 30

In general terms, the efficiency of a system can be thought of as the output per unit input. Which of the expressions is a good mathematical representation of efficiency e of any heat engine?

Back 30

e=W/Qh

Front 31

During the Carnot cycle, the overall entropy ________.

Back 31

remains constant