Physics Chapters 15 & 16
How would decreasing the percentage of greenhouse gases affect the amount of infrared radiation reflected by the atmosphere back toward Earth?
The amount of infrared radiation would decrease.
How would increasing the density of air in the atmosphere affect the amount of infrared radiation returned by the atmosphere back toward Earth?
The amount of infrared radiation would increase.
If you were caught in freezing weather with only a candle for heat, you would be warmer in
an igloo.
Pour a liter of water at 40°C into a liter of water at 20°C and the final temperature of the two becomes
at or about 30°C.
A liter of cold water will warm faster in sunlight in a
black pot.
A liter of hot water will cool to room temperature faster in a
black pot.
Because of trapped air inside, snow is a
both a good insulator and a poor conductor.
A parcel of warmed air rises due to
buoyancy.
A red-hot piece of coal will cool quicker in a
cold room.
A region of expanding air tends to
cool.
If a volume of air is warmed, it expands and tends to
cool.
Newton's law of cooling applies to objects that undergo _________.
cooling or warming
When a bimetallic bar made of copper and iron strips is heated, the bar bends toward the iron strip. The reason for this is
copper expands more than iron.
Aluminum has a specific heat capacity more than twice that of copper. Place equal masses of aluminum and copper wire in a flame and the one to undergo the fastest increase in temperature will be
copper.
If a pizza radiates more energy than it absorbs, its temperature
decreases.
If the temperature of a sample of water at 0°C is slightly increased, its volume
decreases.
Terrestrial radiation is
emitted by Earth.
When we speak about heat we refer to ___________.
energy in transit
When most substances are heated, molecules inside move faster and take up more space, resulting in thermal
expansion.
When you touch a hot potato with your finger, energy flows
from the potato to your finger.
When you touch a cold piece of ice with your finger, energy flows
from your finger to the ice.
A good absorber of radiation is a
good emitter of radiation.
What type of gas absorbs and re-emits infrared radiation?
greenhouse gases
A substance that heats up relatively slowly has a
high specific heat capacity.
The moderate temperatures of islands throughout the world has much to do with water's
high specific heat capacity.
Materials composed of molecules that absorb large amounts of energy in the form of internal vibrations and rotations have
high specific heats.
An apple pie will be a net emitter of energy when its temperature is
higher than its surroundings.
If the temperature of a sample of water at 4°C is slightly increased, its volume
increases.
If the temperature of a sample of water at 4°C is slightly lowered, its volume
increases.
When a hot object makes thermal contact with a cold object, the direction of
internal energy flow is from hot to cold
Aluminum has a higher specific heat capacity than iron. This means that for equal masses of aluminum and iron, the metal that heats more quickly when the same amount of heat is applied is
iron.
On a cold day your feet feel warmer on a rug than on a tile floor because a rug
is a poorer conductor.
When an object absorbs as much as it radiates
it remains at about the same temperature.
Temperature is most closely related to molecular
kinetic energy.
When an iron ring is heated, the hole becomes
larger.
When we enlarge a photograph of an iron ring, the image of the hole becomes
larger.
Hot sand cools off faster at night than plants and vegetation. This indicates that the specific heat capacity for sand is ___________.
less than that of plants
One of water's interesting thermal properties is that when heated it takes a relatively
long time in changing temperature.
A Thermos bottle has double glass walls with silver coating on the glass surfaces that face each other. The silver coating reduces energy transfer by
radiation.
The form of heat transfer that doesn't depend on a medium is
radiation.
The planet Earth loses heat primarily by
radiation.
Molecules in a region of expanding air more often collide with neighboring molecules that are
receding.
If the specific heat capacity of water were lower than it is, a nice hot bath would be a
shorter experience.
The higher the temperature of an object, the
shorter the wavelengths it radiates.
What is terrestrial radiation?
Terrestrial radiation is infrared radiation emitted by Earth's surface.
Relatively speaking, do high-frequency waves have long wavelengths or short wavelengths? Name an electromagnetic wave with higher frequency than blue light.
Short, ultraviolet
In practice, a good insulator
slows heat flow.
Which of these are good insulators?
wood snow feathers
A block of wood and a block of copper will feel neither hot nor cold to the touch when they each have
your temperature.
When water at 4°C is heated it expands. If it is instead cooled it will
also expand.
Heat travels from the Sun to Earth by the process of _________.
radiation
Does a substance that heats up quickly have a high or a low specific heat capacity?
A low specific heat capacity
Heat energy is measured in units of
- joules - calories
If you wish to expand the volume of a sample of water at 4°C
- lower its temperature a bit. - raise its temperature a bit.
The lower the temperature of an object, the
- lower the frequency of radiation it emits. - longer the wavelengths it radiates.
Blow on your hand with your mouth open. Then do the same with your lips puckered and you'll find
- the breath from puckered lips is cooler. - a difference in temperatures.
Which body glows with electromagnetic waves?
- the earth - the sun - you and your classmates
The amount of heat needed to raise the temperature of 1 g of water by 1°C is ___________.
1 calorie
Room temperature on the Kelvin scale is about
300 K.
The amount of heat needed to raise the temperature of 1 gram of water by 1°C is
4.19 joules.
When 10 grams of hot water cool by 1°C, the amount of heat given off is
41.9 joules.
Before ice can form on a lake, all the water in the lake must be cooled to
4°C.
Which will normally warm faster: a black pot of cold water or a silvered pot of cold water? Which will cool faster?
Black, black
Which unit represents the most energy?
Calorie
Which temperature scales have equal sized degrees?
Celsius and Kelvin
Which temperature scale has the smallest sized degrees?
Fahrenheit
In which direction does heat flow spontaneously between hot and cold objects?
From high temperature to low temperature
Why do substances expand when their temperature is increased?
Higher-temperature substances have greater molecular motion.
Why is ice less dense than water?
Ice crystallizes with an open structure, and the gaps that form between the water molecules in ice increase its volume.
Does a good insulator prevent heat from escaping or slow its passage?
Insulators slow the passage of heat.
Does a hot object contain internal energy or does it contain heat?
Internal energy
What determines whether an object is a net absorber or a net emitter of radiant energy at a given time?
It is determined by the temperature of the object relative to its surroundings. Hotter objects are net emitters.
A temperature difference of 10 Celsius degrees is also equal to a temperature difference of 10 on the
Kelvin scale.
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.
Can an object be both a good absorber and a good reflector at the same time?
No. A good absorber reflects very little light.
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.
Why are materials such as wood, fur, feathers, and even snow good insulators?
Outer electrons in these materials are firmly attached.
How does the peak frequency of radiant energy relate to the absolute temperature of the radiating source?
The peak frequency increases as temperature increases.
Which will undergo the greater rate of cooling: a red-hot poker in a warm oven or a red-hot poker in a cold room (or do both cool at the same rate)?
The poker in the cold room cools fastest.
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.
How is heat similar to and different from internal energy?
They are both forms of energy, but heat flows, whereas internal energy does not.
Long ago a runaway greenhouse effect transformed the planet
Venus.
How does the specific heat capacity of water compare with the specific heat capacities of other common materials?
Water has a higher specific heat capacity than most common materials.
Why does all the water in a lake have to be cooled to 4°C before the surface water can be cooled below 4°C?
When water is cooled to 4°C, it sinks and deeper, warmer, water rises to the surface.
If you measure the width of an outdoor barn with a steel tape on a very cold day, your measured width will be
a bit long.
The air in your room is composed of molecules that have
a wide variety of speeds.
Metals are good conductors of both heat and electricity due to
looseness of outer electrons in metal atoms.
The reason you can walk barefoot on red-hot coals of wood without burning your feet mainly involves
low conductivity of the coals.
A substance that cools down faster than others has a
low specific heat capacity.
A substance that heats up relatively quickly has a
low specific heat capacity.
The fact that desert sand is very hot in the day and very cold at night is evidence that the specific heat capacity of sand is relatively
low.
Due to the presence of ice crystals in nearly frozen liquid water, the density of water is
lower.
When coal dust is spread on snow on a sunny day
more melting occurs.
Pour two liters of water at 40°C into one liter of water at 20°C and the final temperature of the two becomes
more than 30°C.
The specific heat capacity is highest for substances that absorb or release large quantities of heat for correspondingly
small temperature changes.
A substance with a high thermal inertia has a high
specific heat capacity.
It is commonly thought that a can of beverage will cool faster in the coldest part of a refrigerator. Knowledge of Newton's law of cooling
supports this common knowledge.
Heat energy travels from an object with a high
temperature to an object with a lower temperature.
Heat normally flows from objects of high
temperature to objects of low temperature.
Waves emitted by the Sun and terrestrial wave emissions are
the same except for their frequencies and wavelengths.