Module 3 Part 2

If you double the absolute temperature of a star, its power output increases by a factor of

16

If you double the radiating surface area of a star, its power output increases by a factor of

2

You are watching a science fiction movie where people on a space ship are traveling around the universe observing stars with different temperatures. Which of the following stars has the lowest surface temperature?

A reddish star

The first law of thermodynamics is a re - statement of the law of

Conservation of energy

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

Convection

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

Convection

Why are good thermal conductors generally good electric conductors also?

Electron motion is responsible for determining both properties

Which of the following quantities is not conserved?

Entropy

Why does an ice cube feel cold?

Heat from your hand enters the cube by conduction

A shiny, white transparent surface prevents heat transfer because

It has emissivity of zero and reflects all light that strikes it

Which temperature scale has 373 as the boiling point of water?

Kelvin

Lead sinkers actually float on the surface of liquid mercury. Which takes up more space: 1 kg of mercury or 1 kg of lead?

Lead

Which temperature scale has 273 as the boiling point water?

No scale

Consider water that freezes into ice when put in your freezer, so the water goes from being disordered to being relatively ordered. Please explain if the freezing of the ice violated the second law of thermodynamics

No the second law is not violated; the entropy of the universe still increased. Although locally the ice froze and its entropy went down, there is a greater entropy increase due to the heat being dissipated outward from the freezer coils. So when you add it all up, the entropy of the universe increased.

Suppose you try to cool your home in the summer by letting heat flow from your house to your neighbor's home. You will

Not get far, because of the zeroth law of thermodynamics

Freezing is a _______ ______ that requires energy ________ for the melting system.

Phase transition; release

In the poem "When You Are Old" by William Butler Yeats there is the following concluding line: "and bending down beside the glowing bars, murmur, a little sadly, how love fled and paced upon the mountains overhead and hid his face amid a crowd of stars." The glowing bars refer the metal bars that hold wood in a fireplace and they are transmitting heat energy by

Radiation and conduction

"The entropy of an isolated system never decreases." Which Law of Thermodynamics is this?

Second

You are riding in a hot air balloon. You have not used the burner for some time and the balloon begins to sink. Assuming that no air is allowed to leave or enter the balloon,

The average density of the balloon because greater than the surrounding air and the buoyant force on the balloon because less than its weight

Housing and natural animal insulation works because

The insulating materials trap air and prevent convection

You fill two identical mugs with coffee, but the coffee in one mug is at a higher temperature than that in the other mug. You place the two mugs simultaneously in a microwave oven and turn it on briefly. As a result, you add 1 joule of thermal energy to each mug. Which mug experiences the larger increase in entropy (if any)?

The mug containing the colder coffee experiences the larger increase in entropy.

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

The nail is a good conductor of heat

"Two objects in thermal equilibrium with a third object are in thermal equilibrium with each other." Which Law of Thermodynamics is this?

Zeroth

It is a hot summer day and your friend's apartment has no air conditioning. However, a brand new refrigerator lies unopened in the center of the living room. Being a creative person, your friend closes all the doors and windows of the apartment, unpacks the refrigerator, plugs it in, and turns it on. Your friend then opens the refrigerator door and uses a small fan to circulate the air past the refrigerator and throughout the room. After the refrigerator has operated for a few minutes, the average temperature in the room is

higher than it was before

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

radiation carries heat downward toward the fire fighter and the aluminum tent reflects most of that radiation