Question 1

Why does an ice cube feel cold?

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

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?

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

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

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

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

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

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?

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.

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

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 ?

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

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

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