Q: A gas in a cylinder with a movable piston undergoes an isobaric expansion from $$V_i = 2\ \mathrm{m}^3 to$$ $$V_f = 4\ \mathrm{m}^3 at a $$constant pressure of $$p = 2000\ \mathrm{Pa}. $$What is the work done ON the gas during this process?

$$W = -p \Delta V = -2000 \times (4-2) = -4000\ \mathrm{J}$$

Question 1

A gas in a cylinder with a movable piston undergoes an isobaric expansion from $$V_i = 2\ \mathrm{m}^3 to$$ $$V_f = 4\ \mathrm{m}^3 at a $$constant pressure of $$p = 2000\ \mathrm{Pa}. $$What is the work done ON the gas during this process?

Accepted Answer

$$W = -p \Delta V = -2000 	imes (4-2) = -4000\ \mathrm{J}$$

Question 2

Which of the following best describes an isochoric process for an ideal gas?

Accepted Answer

The volume remains constant and no work is done: $$W = 0$$

Question 3

A gas is compressed adiabatically in a well-insulated cylinder. Which of the following statements is true?

Accepted Answer

No heat is transferred: $$Q = 0$$, and the change in thermal energy equals the work done: $$\Delta E_{th} = W$$

Question 4

Which equation correctly expresses the First Law of Thermodynamics for a closed system?

Accepted Answer

$$\Delta E_{th} = Q + W$$

Question 5

A monatomic ideal gas undergoes a temperature increase of $$\Delta T$$ during an isochoric process. What is the change in thermal energy?

Accepted Answer

$$\Delta E_{th} = \frac{3}{2} n R \Delta T$$

Question 6

During an isothermal expansion of an ideal gas, which of the following is true?

Accepted Answer

The change in thermal energy is zero: $$\Delta E_{th} = 0$$

Question 7

A gas is heated at constant volume. Which of the following statements is correct?

Accepted Answer

All the heat added increases the internal energy: $$Q = \Delta E_{th}$$

Question 8

Which of the following is the correct expression for the work done ON an ideal gas during an isothermal process?

Accepted Answer

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

Question 9

A system absorbs 500 J of heat from the environment and does 200 J of work on the environment. What is the change in the system's thermal energy?

Accepted Answer

$$\Delta E_{th} = Q + W = 500 + (-200) = 300\ \mathrm{J}$$

Question 10

Which of the following best describes the difference between work and heat as forms of energy transfer?

Accepted Answer

Work is mechanical (force and displacement), heat is thermal (temperature difference).

Question 11

A gas expands isothermally from $$V_i to$$ $$V_f. $$Which of the following is true about the sign of the work done ON the gas?

Accepted Answer

The work done ON the gas is negative: $$W \u003c 0$$

Question 12

In which process is the area under the $$pV$$ curve always zero?

Accepted Answer

Isochoric process

Question 13

A diatomic ideal gas undergoes an adiabatic compression, raising its temperature by $$\Delta T. $$What is the change in thermal energy?

Accepted Answer

$$\Delta E_{th} = \frac{5}{2} n R \Delta T$$

Question 14

A gas is compressed in a well-insulated cylinder by a steady force. What happens to the temperature of the gas?

Accepted Answer

The temperature increases.

Question 15

Which of the following statements about the calorie is correct?

Accepted Answer

1 cal is the quantity of heat needed to change the temperature of 1 g of water by 1°C.

Question 16

A gas is taken from state $$i to $$state $$f$$ along three different paths (A, B, and C) on a $$pV$$ diagram. For which process is the heat transfer the largest?

Accepted Answer

The process with the largest area under the curve (most negative work), so $$Q_B \u003e Q_A \u003e Q_C if$$ $$|W_B| \u003e |W_A| \u003e |W_C|.$$

Question 17

Which of the following is a correct statement about thermal equilibrium?

Accepted Answer

A system is in thermal equilibrium when it is at the same temperature as the environment.

Question 18

A gas is compressed at constant pressure, and its temperature increases. Which of the following is true?

Accepted Answer

The work done ON the gas is positive, and $$Q \u003e 0 if$$ $$\Delta E_{th} \u003e W.$$

Question 19

Which of the following best describes the sign conventions for heat and work in thermodynamics?

Accepted Answer

Heat added to the system: $$Q \u003e 0$$; work done ON the system: $$W \u003e 0$$

Work, Heat, and the First Law of Thermodynamics: Study Notes

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