Q: A 2 kg block of copper ($$c = 385 \ \mathrm{J/(kg \cdot K)}) is $$heated from $$20^\circC to$$ $$80^\circC. $$How much heat is required?

$$Q = 2 \times 385 \times (80 - 20) = 46,200 \ \mathrm{J}$$

Q: The heat required to melt 0.2 kg of ice at $$0^\circC ($$latent heat of fusion for ice $$L_f = 334,000 \ \mathrm{J/kg}) is$$:

$$Q = 0.2 \times 334,000 = 66,800 \ \mathrm{J}$$

Q: A room has single-pane windows with a total area of $$4 \ \mathrm{m}^2. $$The inside temperature is $$15^\circC $$and the outside is $$5^\circC. If $$the glass thickness is $$0.5 \ \mathrm{cm}$$ and $$k = 0.84 \ \mathrm{W/(m \cdot K)}$$, what is the minimum power required to maintain the temperature?

$$P = \frac{0.84 \times 4 \times (15 - 5)}{0.005} = 6,720 \ \mathrm{W}$$

Question 1

Which of the following statements best describes the First Law of Thermodynamics?

Accepted Answer

The change in internal energy of a system equals the heat added to the system plus the work done on the system: $$\Delta E_{sys} = Q + W$$

Question 2

A gas in a piston is compressed isothermally from an initial volume $$V_i to a $$final volume $$V_f at $$temperature $$T. $$What is the work done by the gas during this process?

Accepted Answer

$$W = -nRT \ln \left( \frac{V_f}{V_i} \right)$$

Question 3

Which of the following is NOT a mechanism of heat transfer?

Accepted Answer

Compression

Question 4

A 2 kg block of copper ($$c = 385 \ \mathrm{J/(kg \cdot K)}) is $$heated from $$20^\circC to$$ $$80^\circC. $$How much heat is required?

Accepted Answer

$$Q = 2 	imes 385 	imes (80 - 20) = 46,200 \ \mathrm{J}$$

Question 5

During which process is the work done by an ideal gas zero?

Accepted Answer

Isochoric process

Question 6

A 0.5 kg block of ice at $$-10^\circC is $$placed in 3 kg of water at $$20^\circC. $$Which equation would you use to find the final equilibrium temperature, assuming no heat loss to the environment?

Accepted Answer

$$Q_{lost} = Q_{gained}$$

Question 7

Which of the following best describes the difference between heat and thermal energy?

Accepted Answer

Thermal energy is the energy contained within a system, while heat is energy transferred due to a temperature difference.

Question 8

A metal rod of length $$L$$ and cross-sectional area $$A$$ conducts heat from a hot reservoir at $$T_H to a $$cold reservoir at $$T_C. $$Which equation gives the rate of heat transfer by conduction?

Accepted Answer

$$\frac{Q}{t} = kA \frac{T_H - T_C}{L}$$

Question 9

Which of the following scenarios is an example of adiabatic expansion?

Accepted Answer

A gas rapidly expands when a pressurized bottle is uncapped, causing the temperature to drop.

Question 10

The heat required to melt 0.2 kg of ice at $$0^\circC ($$latent heat of fusion for ice $$L_f = 334,000 \ \mathrm{J/kg}) is$$:

Accepted Answer

$$Q = 0.2 	imes 334,000 = 66,800 \ \mathrm{J}$$

Question 11

Which of the following best describes the process of convection?

Accepted Answer

Thermal energy transfer by the mass movement of fluid particles.

Question 12

A room has single-pane windows with a total area of $$4 \ \mathrm{m}^2. $$The inside temperature is $$15^\circC $$and the outside is $$5^\circC. If $$the glass thickness is $$0.5 \ \mathrm{cm}$$ and $$k = 0.84 \ \mathrm{W/(m \cdot K)}$$, what is the minimum power required to maintain the temperature?

Accepted Answer

$$P = \frac{0.84 	imes 4 	imes (15 - 5)}{0.005} = 6,720 \ \mathrm{W}$$

Question 13

Which equation describes the rate of energy emission by a black body due to thermal radiation?

Accepted Answer

$$\frac{Q}{t} = e \sigma A T^4$

Question 14

A 1.5 kg sample of water at $$20^\circC is to be $$frozen into ice at $$-12^\circC. $$Which steps must be considered in calculating the total energy removed?

Accepted Answer

Cooling water to $$0^\circC$$, freezing at $$0^\circC$$, cooling ice to $$-12^\circC$$

Question 15

Which of the following is true for an isothermal process involving an ideal gas?

Accepted Answer

The internal energy of the gas remains constant.

Question 16

For a monatomic ideal gas, what is the difference between the molar specific heats at constant pressure and constant volume?

Accepted Answer

$$C_P - C_V = R$$

Question 17

Newton’s Law of Cooling states that:

Accepted Answer

The rate of cooling is proportional to the temperature difference between the object and its surroundings.

Question 18

Which of the following best explains why the inside of a mining tunnel is cooler than the surface during a hot day?

Accepted Answer

Thermal conduction through the ground is slow, so the tunnel temperature reflects the average annual surface temperature rather than daily extremes.

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