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.

Work, Heat, and the First Law of Thermodynamics: A Comprehensive Study Guide

스터디 가이드 - 연습 문제

학습 가이드 - 플래시카드