Question 1

Which of the following best describes a non-thermal equilibrium relationship between three objects A, B, and C, as discussed in the study materials?

Accepted Answer

A is in thermal equilibrium with B, B is in thermal equilibrium with C, but A is not in thermal equilibrium with C.

Question 2

A student reads the temperature in a freezer as $$-x \ ^\circ \mathrm{C}$$, then mistakenly omits the negative sign and converts $$x \ ^\circ \mathrm{C} to $$Fahrenheit using $$F = \frac{9}{5}C + 32. $$Oddly, the result matches the correct Fahrenheit temperature for $$-x \ ^\circ \mathrm{C}. $$What is the value of $$x$$?

Accepted Answer

$$x = 16$$

Question 3

Why is the bimetallic strip in a thermometer shaped as a spiral?

Accepted Answer

To amplify the small expansion difference between the two metals into a larger, measurable movement.

Question 4

At what temperature is the separation between the two metals in a bimetallic strip thermometer expected to be smallest?

Accepted Answer

At the lowest temperature measured.

Question 5

Why are two different metals used in a bimetallic strip thermometer instead of just one?

Accepted Answer

To create a larger difference in thermal expansion, resulting in measurable bending.

Question 6

A double-paned window has two glass panes, each $$0.80 \ \mathrm{cm}$$ thick, separated by a $$1.00 \ \mathrm{cm}$$ air gap. The inside surface temperature is $$15 \ ^\circ \mathrm{C}$$, and the outside is $$-10 \ ^\circ \mathrm{C}. If $$the thermal conductivity of glass is $$k_{glass} = 0.8 \ \mathrm{W}/\mathrm{m} \cdot \mathrm{K}$$ and air is $$k_{air} = 0.025 \ \mathrm{W}/\mathrm{m} \cdot \mathrm{K}$$, what is the total rate of heat transfer per square meter?

Accepted Answer

$$q = 7.1 \ \mathrm{W}/\mathrm{m}^2$$

Question 7

If the air gap in a double-paned window is increased, what happens to the rate of heat transfer through the window?

Accepted Answer

It decreases because the thermal resistance of the air gap increases.

Question 8

A $$70 \ \mathrm{kg}$$ ice skater exerts pressure on ice with skate blades of area $$20 \ \mathrm{mm} 	imes 25 \ \mathrm{cm}. If $$the pressure is $$1.1 \ \mathrm{atm}$$ and the temperature of the ice is $$-0.5 \ ^\circ \mathrm{C}$$, will the ice melt under the skater? Use the phase diagram of water for your answer.

Accepted Answer

No, because the pressure is not high enough to lower the melting point below $$-0.5 \ ^\circ \mathrm{C}.$$

Question 9

Which equation correctly relates Celsius and Fahrenheit temperatures?

Accepted Answer

$$F = \frac{9}{5}C + 32$$

Question 10

A glass window has an area of $$1.50 \ \mathrm{m}^2$$ and thickness $$0.80 \ \mathrm{cm}. $$The inside temperature is $$15 \ ^\circ \mathrm{C}$$ and the outside is $$-10 \ ^\circ \mathrm{C}. $$What is the rate of heat conduction through the window? ($$k_{glass} = 0.8 \ \mathrm{W}/\mathrm{m} \cdot \mathrm{K})$$

Accepted Answer

$$q = 36 \ \mathrm{W}$$

Question 11

Which of the following best explains why pressure can cause ice to melt under a skate blade?

Accepted Answer

Pressure decreases the melting point of ice, allowing it to melt at lower temperatures.

Question 12

If a bimetallic strip thermometer is placed in a very cold environment, what will happen to the spiral?

Accepted Answer

It will coil tighter due to contraction of the metals.

Question 13

A window is made of a single pane of glass $$1.60 \ \mathrm{cm}$$ thick with the same area and temperature difference as a double-paned window. How does its rate of heat conduction compare to the double-paned window with an air gap?

Accepted Answer

It is higher because the absence of the air gap reduces thermal resistance.

Question 14

Which of the following is a plausible reason for using a bimetallic strip instead of a single metal in a thermometer?

Accepted Answer

A single metal would not bend enough to be measurable.

Question 15

If the temperature difference across a window increases, what happens to the rate of heat transfer?

Accepted Answer

It increases.

Question 16

Which of the following best describes the function of a bimetallic strip in a thermometer?

Accepted Answer

It bends due to differential expansion of two metals, moving a pointer to indicate temperature.

Question 17

A student wants to graph temperature versus time for a process with a constant rate of heat transfer. What should the graph look like?

Accepted Answer

A straight line with a positive slope.

Question 18

Which of the following is the correct formula for the rate of heat conduction through a material?

Accepted Answer

$$q = kA \frac{\Delta T}{d}$$

Thermal Physics: Temperature, Heat Transfer, and Phase Changes – Study Notes

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