Question 1

Why does an ice cube feel cold?
A) Heat from your hand enters the cube by convection.
B) Cold from the cube enters your hand by convection.
C) Heat from your hand enters the cube by conduction.
D) Cold from the cube enters your hand by conduction.

Accepted Answer

Heat transfer occurs from your hand to the ice cube through conduction, as heat moves from the warmer object (your hand) to the colder one (the ice cube). Cold does not move; rather, heat does.

Question 2

Wind is one of nature's ways of transferring energy through
A) conduction.
B) convection.
C) transmission.
D) radiation.

Accepted Answer

Wind is a result of the movement of air masses due to temperature differences, which is a form of convection. Convection involves the transfer of heat through the movement of fluids (gases or liquids), which in the case of wind, is the movement of air.

Question 3

Why are good thermal conductors generally good electric conductors also?
A) Heat and electricity are the same things.
B) The molecules in both don't move around very much.
C) Electron motion is responsible for determining both properties.
D) The answer depends on the specific metal.

Accepted Answer

Good thermal conductors are often also good electrical conductors because both properties are largely determined by the ability of electrons to move freely within the material. In metals, which are typically good conductors of both heat and electricity, the outer electrons are not bound to any particular atom and can move freely, facilitating the transfer of both thermal energy and electrical charge.

Question 4

A pedestrian bridge crosses a street. This bridge is entirely supported by columns from below. A gap at each end of the bridge separates the bridge's surface from the sidewalks leading to the bridge. The width of each gap changes with time. This width is smallest
A) on hot days.
B) at noon.
C) at midnight.
D) on cold day.

Accepted Answer

The width of the gap is smallest on hot days because materials expand when heated, causing the bridge to expand and reduce the gap size.

Question 5

The neighborhood children are playing and one has lost a pocketful of change. As a result they all decide to do a close inspection of the sidewalk. They notice that there are gaps in between the sidewalk filled with a felt - like material. These gaps will prevent
A) high stress due to electron "collisions"
B) high stress due to thermal expansion.
C) high stress due to brittleness
D) high stress due to the weight of the sidewalk

Accepted Answer

The felt-like material in the gaps between sidewalk sections is used to accommodate thermal expansion. As the temperature changes, the concrete can expand or contract without causing cracks or damage, thus preventing high stress due to thermal expansion.

Question 6

People fighting forest fires carry emergency tents that have shiny aluminum outer surfaces. If there is trouble, a fire fighter can lie under the tent to block the heat from burning trees overhead. The tent helps because
A) conduction carries heat downward toward the fire fighter and the aluminum tent conducts that heat harmlessly into the ground.
B) radiation carries heat downward toward the fire fighter and the aluminum tent reflects most of that radiation.
C) convection carries heat downward toward the fire fighter and the aluminum tent blocks most of the heat carried by convection.
D) both conduction and radiation carry heat downward toward the fire fighter and the aluminum tent blocks most of that heat.

Accepted Answer

Radiation is the primary method by which heat from a forest fire would be transferred to a firefighter lying under a tent. The shiny aluminum surface of the tent reflects most of the radiant heat, protecting the firefighter.

Question 7

You are a mechanic in a garage and are working on a carburetor that is made of metal, has a glass inspection window and plastic gears for the choke. If all three types of material are at the same temperature and each type of material is in contact with the other two, then
A) heat will flow from the plastic to the glass, and from the glass to the metal.
B) heat will flow from the metal to the glass, and from the glass to the plastic.
C) heat will flow from the glass to both the plastic and the metal.
D) no heat will flow between any parts.

Accepted Answer

If all materials are at the same temperature, there is no temperature gradient to drive heat flow, so no heat will flow between the parts.

Question 8

Suppose you are teaching a science course and have prepared a demonstration to teach how a thermometer works. When you plunge the thermometer into hot water, one of your students points out that the mercury in the thermometer actually went down a little bit before it shot up. It behaved in such a way because
A) The water pressure squeezed in on the mercury.
B) The mercury contracted at first because of the temperature shock.
C) The glass expanded before the mercury had a chance to, creating space.
D) The thermometer lost heat to the surrounding water.

Accepted Answer

The glass of the thermometer expands when it first comes into contact with the hot water, before the mercury inside has a chance to expand. This initial expansion of the glass creates more space for the mercury, making it appear as if the mercury level drops before it begins to expand and rise in response to the heat.

Question 9

The surface of the moon is exposed to full solar radiation because it has no atmosphere. Why then does the moon not heat up endlessly until it disintegrates?
A) Convection in the soil carries energy away.
B) Its temperature rises until it is able to radiate heat away into space as fast as it arrives from the sun.
C) It has disintegrated but the light just hasn't reached us yet.
D) Because it is isolated from the sun by empty space, the sun's heat can't reach it (only light can) and they don't experience any changes in temperature.

Accepted Answer

The moon heats up until it reaches a temperature where it can radiate heat back into space as quickly as it absorbs it from the sun. This balance prevents it from endlessly heating up.

Question 10

Soil heats up much faster than water when the two are exposed to sunlight. Use that fact and your understanding of heat transfer to predict which way the wind will blow near the surface of the earth as the sun rises near the seashore.
A) The surface wind will blow from the land toward the water.
B) The surface wind will blow alternately back and forth along the shore, parallel to the boundary between land and water. It will reverse directions every few minutes.
C) The surface wind will blow steadily in one direction along the shore, parallel to the boundary between land and water.
D) The surface wind will blow from the water toward the land.

Accepted Answer

As the sun rises, the land heats up faster than the water. This causes the air above the land to warm up, expand, and rise, creating a low-pressure area. Cooler, denser air from over the water moves in to replace it, resulting in a wind blowing from the water toward the land, known as a sea breeze.

Question 11

A common glass thermometer contains a red or silver liquid that rises upward in a glass tube as the temperature of the thermometer increases. The liquid moves up the tube because
A) only the glass contracts as its temperature decreases, so the liquid moves up the tube to occupy more of the tube's internal space.
B) while both the glass and the liquid contract as their temperatures increase, the glass contracts more rapidly than the liquid does.
C) the pressure of gas above the liquid decreases as its temperature rises and the liquid is sucked upward in the glass tube.
D) while both the glass and the liquid expand as their temperatures increase, the liquid expands more rapidly than the glass does.

Accepted Answer

The liquid in a thermometer expands more rapidly than the glass as temperature increases, causing it to rise in the tube.

Question 12

Trace the transfer of energy that comes from your food.

Accepted Answer

The answer of Trace the transfer of energy that comes...

Question 13

Suppose you take an interest in astronomy. You are at an astronomy conference and you are listening to a presentation where a scientist is describing a new planet. The scientist says "The planet Xhhroylg is completely solid and convects heat from its inner core towards the surface at a rapid rate. Although no electromagnetic radiation escapes through its dense atmosphere, its heat conducts through the reaches of outer space and that explains how it cools down." Please discuss three instances where, scientifically, this presenter is incorrect.

Accepted Answer

The answer of Suppose you take an interest in astronomy....

Question 14

A thermos may be thought of as a glass bottle within another, which are joined (sealed) together at the top. The space between the bottles may be evacuated, and the surface of the inner bottle may be silvered (coated with reflective material).What heat transfer mechanisms, if any would be inhibited by
-A silvered, evacuated thermos;

Accepted Answer

The answer of A thermos may be thought of as...

Question 15

A thermos may be thought of as a glass bottle within another, which are joined (sealed) together at the top. The space between the bottles may be evacuated, and the surface of the inner bottle may be silvered (coated with reflective material).What heat transfer mechanisms, if any would be inhibited by
-a clear thermos, not evacuated;

Accepted Answer

The answer of A thermos may be thought of as...

Question 16

A thermos may be thought of as a glass bottle within another, which are joined (sealed) together at the top. The space between the bottles may be evacuated, and the surface of the inner bottle may be silvered (coated with reflective material).What heat transfer mechanisms, if any would be inhibited by
-a clear, evacuated thermos, and

Accepted Answer

The answer of A thermos may be thought of as...

Question 17

A thermos may be thought of as a glass bottle within another, which are joined (sealed) together at the top. The space between the bottles may be evacuated, and the surface of the inner bottle may be silvered (coated with reflective material).What heat transfer mechanisms, if any would be inhibited by
-a silvered thermos only.

Accepted Answer

The answer of A thermos may be thought of as...

Question 18

Why does the handle of a metal spoon submerged in boiling soup feel hot ?
A) from the soup is transferred through the spoon by convection.
B) The spoon has given up all its cold to the soup.
C) Heat from the soup is transferred through the spoon by conduction.
D) Heat from the soup is transferred through the spoon by radiation.

Accepted Answer

Heat from the soup is transferred through the spoon by conduction. This is because metal is a good conductor of heat, allowing the thermal energy from the hot soup to move along the spoon to the handle.

Question 19

The gulf stream is one of nature's ways of transferring energy through
A) conduction.
B) convection.
C) transmission.
D) radiation.

Accepted Answer

The Gulf Stream transfers energy primarily through convection, as it is a warm ocean current that moves warm water from the Gulf of Mexico along the eastern coastlines of the United States and across the Atlantic Ocean. This process involves the movement of heat through the physical movement of the water itself.

Question 20

When cooking a potato in a conventional oven it is useful to stick a nail in it, which makes it cook faster. This is because
A) the nail is a good radiator of heat
B) the nail promotes convection in the potato
C) the nail is a good conductor of heat
D) the nail gets much hotter than anything in the oven

Accepted Answer

The nail conducts heat into the center of the potato more efficiently than the potato can by itself, because metal is a better conductor of heat than the potato's flesh. This reduces cooking time by distributing heat more evenly inside the potato.

Quiz 7: Heat and Phase Transitions

Why does an ice cube feel cold?

Wind is one of nature's ways of transferring energy through

Why are good thermal conductors generally good electric conductors also?

A pedestrian bridge crosses a street. This bridge is entirely supported by columns from below. A gap at each end of the bridge separates the bridge's surface from the sidewalks leading to the bridge. The width of each gap changes with time. This width is smallest

The neighborhood children are playing and one has lost a pocketful of change. As a result they all decide to do a close inspection of the sidewalk. They notice that there are gaps in between the sidewalk filled with a felt - like material. These gaps will prevent

People fighting forest fires carry emergency tents that have shiny aluminum outer surfaces. If there is trouble, a fire fighter can lie under the tent to block the heat from burning trees overhead. The tent helps because

You are a mechanic in a garage and are working on a carburetor that is made of metal, has a glass inspection window and plastic gears for the choke. If all three types of material are at the same temperature and each type of material is in contact with the other two, then

The surface of the moon is exposed to full solar radiation because it has no atmosphere. Why then does the moon not heat up endlessly until it disintegrates?

Soil heats up much faster than water when the two are exposed to sunlight. Use that fact and your understanding of heat transfer to predict which way the wind will blow near the surface of the earth as the sun rises near the seashore.

A common glass thermometer contains a red or silver liquid that rises upward in a glass tube as the temperature of the thermometer increases. The liquid moves up the tube because

Trace the transfer of energy that comes from your food.

Why does the handle of a metal spoon submerged in boiling soup feel hot ?

The gulf stream is one of nature's ways of transferring energy through

When cooking a potato in a conventional oven it is useful to stick a nail in it, which makes it cook faster. This is because