PHYSICS FINAL

Which one of these cites the lowest temperature?

(A) 270 K b. 32 F c. 0 C d. 273 K

atmospheric pressure decreases with increasing

(A.) altitude b. amounts of sunshine c. temperature d. speed of molecules in the air

What is the lowest possible temperature on the Celsius scale? On the Kelvin scale?

-273 C, 0 K

How many calories are needed to change the temperature of 1 g of water by 1°C? To melt 1 g of ice at 0°C? To vaporize 1 g of boiling water at 100°C?

1 calorie, 80 calories, 540 calories

The precise volume of water of the same mass depends on the temperature of the water. Rank from greatest to least the volumes of water of the same mass at the following temperatures:

10 C, 0 C, 4 C

A 1 kg balloon at equilibrium in the air is buoyed up with a force of __________.

10 newtons

Discuss the first and second laws of thermodynamics in terms of whether or not exceptions occur.

1st law: no exceptions; 2nd law: exceptions are possible but improbable.

Calculate the quantity of heat absorbed by 50 g of water that warms from 30∘C to 90∘C

3000 cal

Radioactive decay of granite and other rocks in Earth's interior provides sufficient energy to keep the interior molten, to heat lava, and to provide warmth to natural hot springs. This is due to the average release of about 0.03 J per kilogram each year. Find an increase in temperature for a thermally insulated chunk of granite that takes about 13.2 million years to change temperature. (Assume that the specific heat capacity cc of granite is 800 J/kg⋅C. Use the equation Q=cmΔT)

495 C

The weight of the atmosphere above 1 m^2 of Earth's surface is about 100,000 N. Density, of course, becomes less with altitude. But suppose the density of air were a constant 1.2 kg/m^3 Calculate where the top of the atmosphere would be.

8.5 km

Calculate the ideal efficiency of an engine in which fuel is heated to 3100 K and the surrounding air is 200 K

94%

Distinguish between a calorie and a Calorie.

A Calorie is 1000 calories

How does a plasma differ from a gas?

A plasma is made up of ionized atoms

What is meant by a system?

A well-defined group of atoms or objects

Rank the volume of air in the glass, from greatest to least, when it is held A. near the surface as shown. B. 1 m beneath the surface. C. 2 m beneath the surface.

A, B, C

On a perfect fall day, you are hovering at low altitude in a hot-air balloon, accelerated neither upward nor downward. The total weight of the balloon, including its load and the hot air in it, is 17000 N . A. Find the weight of the displaced air B. Find the volume of the displaced air

A. 1.7 x 10^4 N B. 1400 m^3

If you drop a piece of ice on a hard surface, the energy of impact will melt some of the ice. The higher it drops, the more ice will melt upon impact Find the height from which a block of ice should ideally be dropped to completely melt it that falls without air drag.[Hint: Equate the joules of gravitational potential energy to the product of the mass of ice and its heat of fusion (in SI units, 335,000 J/kgJ/kg). Do you see why the answer doesn't depend on mass?]

A. 34 km B. no, the answer does not depend on mass

The quantity of heat Q that changes the temperature ΔT of a mass mm of a substance is given by Q=cmΔT, where c is the specific heat capacity of the substance. For example, for H2O, c=1cal/g∘C. And for a change of phase, the quantity of heat QQ\ that changes the phase of a mass mm is Q=mL, where L is the heat of fusion or heat of vaporization of the substance. For example, for H2O, the heat of fusion is 80 cal/g (or 80 kcal/kg) and the heat of vaporization is 540 cal/g (or 540 kcal/kg) A. Use these relationships to determine the number of calories to change 1.1 kg of 0∘C ice to 0∘C ice water B. Use these relationships to determine the number of calories to change 1.1 kg of 0∘C ice water to 1.1 kg of 100∘C boiling water C. Use these relationships to determine the number of calories to change 1.1 kg of 100∘C boiling water to 1.1 kg of 100∘C steam D. Use these relationships to determine the number of calories to change 1.1 kg of 0∘C ice to 1.1 kg of 100∘C steam

A. 88 kcal B. 110 kcal C. 590 kcal D. 790 kcal

A. Which of the following would best describe the conductive properties of wood? B. What happens to the conductive properties of wood when it gets very hot? C. If you are able to grab a hot pan and pull it out by the handle without burning yourself, what kind of handle must the pan have, and why? D. Why is one able to walk on red-hot coals without getting one's feet burned? E. How would you walk on red-hot coals without getting your feet burned?

A. It is a good insulator B. It will continue to remain a good insulator C. a wooden handle, because it is the better insulator D. The coals are not good conductors of heat E. Walk fast

The specific heat capacity of steel is 450 J/(kg*C). A. Select the correct equations that show the amount of heat needed to raise the temperature of a 14 kg piece of steel from 0 C to 100 C is 630,000 J B. How does this compare with the heat needed to raise the temperature of the same mass of water through the same temperature difference?

A. Q= cm[delta]T = (450 J/kg*C) (14 kg)(100-0) = 630,000 J B. This value is less than the heat needed to raise the temperature of the same mass of water through the same temperature difference.

You wish to warm 45 kg of water by 20∘C for your bath. A. Select the correct equations that show the amount of heat needed is 900 kcal (900 Cal) B. select the correct equation that shows that this is equivalent to about 3800 kJ

A. Q= cm[delta]T= (1 kcal/(kg*C)) (45 kg) (20 C) = 900 kcal B. (900 kcal) (4.19 kJ/kcal) = 3771 kJ

A. What happens when you heat ice that is at -40 C? B. What happens when you heat ice that is at 0 C? C. What happens when you heat water that is at 0 C? D. What happens when you heat water that is at 100 C?

A. The temperature increases until the ice reaches its melting point B. the temperature stays constant until all the ice is melted C. The temperature increases until it reaches 100 C D. The temperature stays constant until all of the water is boiled

A. Describe what happens to the pressure, volume, and temperature of the gas in the internal combustion engine during the compression stroke B. Describe what happens to the pressure, volume, and temperature of the gas in the internal combustion engine when the spark plug is ignited right after the compression stroke C. Describe what happens to the pressure, volume, and temperature of the gas in the internal combustion engine during the power stroke. D. Describe what happens to the pressure, volume, and temperature of the gas in the internal combustion engine during the exhaust stroke.

A. The volume decreases, but the pressure and temperature of the gas both increase. B. The pressure and temperature will increase, but the volume stays the same. C. The pressure and temperature will decrease, but the volume will increase. D. The volume will decrease, but the pressure and temperature will stay the same.

A. What type of gas absorbs and re-emits infrared radiation? B. How would increasing the density of air in the atmosphere affect the amount of infrared radiation returned by the atmosphere back toward Earth? C. How would decreasing the percentage of greenhouse gases affect the amount of infrared radiation reflected by the atmosphere back toward Earth?

A. greenhouse gases B. The amount of infrared radiation would increase C. The amount of infrared radiation would decrease

A. What happens to the air as it expands? B. How does the air coming out of your mouth feel if you blow on your palm? C. Why does the air coming out of your mouth feel the way it does if you blow on your palm? D. Where is Dr. Hewitt able to hold his hand above the nozzle of the pressure cooker without getting burned by the steam, and why?

A. it cools B. It feels warm if your mouth is open wide and cool if your mouth is open narrow. C. When you breathe out with your lips puckered the air expands. D. He can hold his hand a few inches above the nozzle because the water vapor coming out of the nozzle has expanded and cooled. Submit

A. What do you use a pressure cooker for? B. How does using a pressure cooker affect the amount of internal energy in the water inside the pressure cooker and why? C. How does the pressure exerted by the bubble in the water compare with the atmospheric pressure when the temperature of the water in an open pressure cooker in below 100 C and when it equals 100 C? D. What happens to the water at room temperature if you decrease the atmospheric pressure around it?

A. to prevent boiling and cooling B. It increases the amount of internal energy because it does not allow the heat to boil the water C. The pressure exerted by the bubbles is less than the atmospheric pressure below 100 C and equals the atmospheric pressure at 100∘C. D. It will first boil and then freeze

Does a solid release energy or absorb energy when it changes into a liquid? When it sublimes into a gas?

Absorb, absorb

How does the law of the conservation of energy relate to the first law of thermodynamics?

Adding heat flow to the law of conservation of energy gives the first law of thermodynamics.

Does the air exert a buoyant force on all objects in air or only on objects such as balloons that are very light for their size?

Air exerts a buoyant force on all objects

How do meteorologists express the first law of thermodynamics?

Air temperature rises as heat is added or as pressure is increased.

How much the lengths of various substances change with temperature changes is given by their coefficients of linear expansion, α. The greater the value of α the greater the change in length for a given change in temperature. Three kinds of metal wires, A, B, and C, are stretched between distant telephone poles. From greatest to least, rank the wires in how much they'll sag on a hot summer day. A: Copper, α=17×10−6/∘C B: Aluminum, α=24×10−6/∘C C: Steel, α=11×10−6/∘C

Aluminum, Copper, Steel

In what form does radiant energy travel?

As electromagnetic waves

What happens to the water pressure at the bottom of a geyser when some of the water above gushes out? What is the result?

As water rushes out, the pressure on the remaining water is reduced, so the water boils.

Which will normally warm faster: a black pot of cold water or a silvered pot of cold water? Which will cool faster?

Black, black

Why doesn't energy added to boiling water increase the temperature of the water?

Boiling is a cooling process, so energy is removed as quickly as it is added.

Rank from most to least, the amount of lift on the following airplane wings: A. Area 1000 m2m2 with atmospheric pressure difference of 2.0 N/m2N/m2. B. Area 800 m2m2 with atmospheric pressure difference of 2.4 N/m2N/m2. C. Area 600 m2m2 with atmospheric pressure difference of 3.8 N/m2N/m2.

C, A, B

What is condensation? Is condensation a warming or cooling process?

Condensation is when a gas becomes a liquid. It is a warming process.

When the temperature of ice-cold water is increased slightly, does it undergo a net expansion or a net contraction?

Contraction

Why do you feel uncomfortably warm on a hot and humid day?

Cooling sweat does not evaporate well in humid air.

Rank the boiling-water temperatures in different locations. From largest to smallest

Death valley, sea level, Denver, CO (the "mile-high city")

What is the physicist's term for the measure of the amount of disorder?

Entropy

Distinguish between evaporation and boiling.

Evaporation happens at a liquid surface, whereas boiling occurs in the bulk of the liquid.

In astronomy you may hear temperatures quoted on any of three different temperature scales: the Fahrenheit scale used commonly in the United States, the Celsius scale used internationally, and the Kelvin scale used in science.

Fahrenheit: a hot summer day might be 100; ice cream is stored in freezers at 26 Celsius: Water freezes into ice at 0; liquid water boils at 100; a typical room temperature is 24 Kelvin: the coldest possible temperature is 0; water boils into gas phase at 373.15

What is the role of "loose" electrons in heat conductors?

Free electrons can move through a material carrying heat, jostling atoms and other electrons.

Rank the energies needed for different phase changes for equal amounts of H2O. From largest to smallest

From boiling water to steam, from ice water to boiling water, from ice to ice water.

What three processes occur in every heat engine?

Heat flows into a system from a hot reservoir, work is done by the system, and heat flows out to a cold reservoir

How does the second law of thermodynamics relate to the direction of heat flow?

Heat of itself never flows from a cold object to a hot object.

A strong wind blows over the house shown in the figure. The wind is much stronger over the house's roof than lower down, and the house has an open chimney. A window on the ground floor is open, and so are the doors inside the house. Which way will air flow through the house?

In the window and out the chimney

Does increased atmospheric pressure increase or decrease the boiling point of water? Why?

Increase. Higher pressure collapses the bubbles that form.

Does a good insulator prevent heat from escaping or slow its passage?

Insulators slow the passage of heat

What generally happens to the temperature of rising air? Of sinking air?

It decreases. It increases.

By how much does the density of air increase when it is compressed to half its volume?

It doubles

Which generally expands more for an equal increase in temperature: solids or liquids?

Liquids generally expand more than solids.

Is the study of thermodynamics concerned primarily with microscopic processes or with macroscopic ones? Why?

Macroscopic, because atoms were unknown at the time thermodynamics was created

If you touch the metal sides in an oven with your bare hand, you're in trouble. But hold your hand briefly in the oven air and you're okay. What does this tell you about the relative conductivities of metal and air?

Metal is a good conductor of heat, whereas air is a terrible conductor of heat.

What condition is necessary for a process to be adiabatic?

No heat enters or leaves the system.

Since all objects emit energy to their surroundings, why don't the temperatures of all objects continuously decrease?

Objects that are good emitters are equally good absorbers, so they absorb radiation as well as emit it.

Show that 1000 cal are required to increase the temperature of 10 g of water from 0∘C to 100∘C. The specific heat capacity for water is 1 cal/(g⋅∘C)

Q=cmΔT=(1cal/(g⋅∘C))⋅(10g)⋅(100∘C)=1000cal

Why does warm, moist air form clouds when it rises?

Rising air expands and cools. Water drops condense when moist air cools.

Relatively speaking, do high-frequency waves have long wavelengths or short wavelengths? Name an electromagnetic wave with higher frequency than blue light.

Short, ultraviolet

Do the molecules in a liquid all have about the same speed, or do they have a wide variety of speeds?

Some are slow and some are fast.

Consider the video tutorial you just watched. Suppose we repeat the experiment, but this time place the divider closer to one side of the tube than to the other. How will the speed of the air on the wide and narrow sides of the divider compare? (Assume that burning has a negligible effect on the mass of the air circulating through the tube.)

The air will move faster on the narrow side

What would be the consequence of completely eliminating the greenhouse effect?

The average temperature on the surface of Earth would drop to -18°C

What happens to the hexagonal open structure of ice when sufficient pressure is applied to it?

The crystals are crushed to form the liquid phase.

Northeastern Canada and much of Europe receive about the same amount of sunlight per unit area. Why, then, is Europe generally warmer in the winter?

The gulf stream carries warm, high heat capacity water past the west coast of Europe.

What cooks food faster in a pressure cooker?

The higher temperature of boiling water under pressure cooks the food faster.

What happens to the internal pressure in a fluid flowing in a horizontal pipe when its speed increases?

The pressure decreases when the speed increases

Discuss why water can issue from deep underwater vents at temperatures of some 300∘C without boiling

The pressure of surrounding water acts like a pressure cooker and prevents boiling

What change in pressure occurs in a party balloon that is squeezed to one-third its volume with no change in temperature?

The pressure will increase to three times its original pressure

Why does the direction of coastal winds change from day to night?

The specific heat of water is greater than the specific heat of land. Water cools more slowly at night. The temperature difference drives convection and offshore winds.

What is the third law of thermodynamics?

The temperature of a system can never reach absolute zero.

Is there a distinction between thermal energy and internal energy? Which term do physicists prefer?

Thermal energy emphasizes heat flow, whereas internal energy is the grand total of all energies inside a substance. Physicists prefer internal energy.

How does the weight of mercury in a barometer compare with the weight of an equal cross-section of air from sea level to the top of the atmosphere?

They are equal

What is the zeroth law of thermodynamics?

Two systems in thermal equilibrium with a third system are in equilibrium with each other.

Which of the following changes would make the water balloon more likely to pop? (Ignore effects of convection within the fluid.) select all that apply

Use a liquid that has a lower heat capacity than water; use a thicker balloon

Which of the following most prevents the escape of terrestrial radiation?

Water vapor

Why is evaporation a cooling process?

When the fastest molecules leave during evaporation, the slower, cooler ones remain.

Changes of phase most always require _________.

a transfer of energy

Which one of these represents the largest amount of energy?

a. 5 joules b. 10 calories (C) 1 Calorie d. 100 calories

atmospheric pressure is mainly due to the ________________

a. motion of air molecules b. average temperature of air c. air pressure against Earth's surface (D) weight of air

What is the energy source for the motion of gas in the atmosphere? What prevents atmospheric gases from flying off into space?

a. solar energy, clouds (B.) solar energy, gravity c. geothermal energy, gravity d. geothermal energy, clouds

Air pressure over the surface of a bird's wings decreases when __________.

air speed increases there

As entropy in a system increases, energy in the system _________.

becomes less ordered

a thermos bottle controls heat by __________

conduction, convection, and radiation

Newton's law of cooling applies to objects that undergo _________.

cooling or warming

When air rapidly expands, its temperature normally _________.

decreases

A gas will become plasma when it is __________.

electrically charged

If work is done on a system, does the internal energy of the system increase or decrease? If work is done by a system, does the internal energy of the system increase or decrease?

increase, decrease

Suppose that we replace the aluminum with a mystery metal and repeat the experiment in the video. As in the video, the mass of the metal is the same as that of the water. Room temperature is about 20∘C before the start of the experiment. The water heats up to 40∘C, and the mystery metal heats up to 80∘C. Compared to that of water, the heat capacity of our mystery metal is

one-third as great (Q=mc [delta]T; m is mass, c is heat capacity)

What are the four common phases of matter?

solid, liquid, gas, plasma

When a party balloon is compressed to one-third its volume, gas pressure in the balloon ___________.

triples