Q: Which equation correctly expresses the First Law of Thermodynamics as presented in the lecture?

$$\Delta E_{\text{sys}} = W_{\text{on system}} + Q$$

Question 1

Which equation correctly expresses the First Law of Thermodynamics as presented in the lecture?

Accepted Answer

$$\Delta E_{	ext{sys}} = W_{	ext{on system}} + Q$$

Question 2

A sample of ideal gas is enclosed in a piston. The gas expands at constant pressure from volume $$V_1 to$$ $$V_2. $$What is the work done by the gas during this process?

Accepted Answer

$$W = P (V_2$ - V_1$)$$

Question 3

According to the ideal gas law, if the pressure and temperature of a closed container of gas both decrease by half, what happens to the volume?

Accepted Answer

The volume remains the same.

Question 4

Which process is represented by a vertical line on a PV diagram?

Accepted Answer

Isochoric (constant volume) process

Question 5

On a PV diagram, what does the area under the curve between two points represent?

Accepted Answer

The work done by the gas during the process

Question 6

A gas undergoes an isothermal expansion from $$V_1 to$$ $$V_2 at $$temperature $$T. $$What is the expression for the work done by the gas?

Accepted Answer

$$W = n k_B T \ln \left( \frac{V_2$}{V_1$} \right)$$

Question 7

During a constant volume (isochoric) process, what is the work done by the gas?

Accepted Answer

$$W = 0$$

Question 8

A gas in a piston undergoes a cyclic process represented by a closed loop on a PV diagram. What can be said about the net work done by the gas in one complete cycle?

Accepted Answer

It is equal to the area enclosed by the loop.

Question 9

If a gas expands at constant temperature, which of the following statements is true?

Accepted Answer

The internal energy of the gas does not change.

Question 10

A sample of ideal gas is compressed isobarically (at constant pressure) and its temperature decreases. What is the sign of the heat $$Q$$ transferred to the gas?

Accepted Answer

Negative

Question 11

Which of the following best describes the relationship between pressure and volume for an isothermal process of an ideal gas?

Accepted Answer

$$P V = 	ext{constant}$$

Question 12

In a PV diagram, which process is represented by a horizontal line?

Accepted Answer

Isobaric (constant pressure) process

Question 13

A gas is compressed at constant temperature from $$V_1 to$$ $$V_2. $$What happens to the pressure?

Accepted Answer

It increases.

Question 14

During which process does the internal energy of an ideal gas change only if the temperature changes?

Accepted Answer

Any process

Question 15

A sample of gas is heated at constant volume. What is the sign of the work done by the gas?

Accepted Answer

Zero

Question 16

In a cardiac cycle, the area enclosed by the PV loop represents which physical quantity?

Accepted Answer

The net work done by the heart during one cycle

Question 17

A gas expands isothermally and reversibly. Which of the following is true about the heat $$Q$$ and work $$W$$ for the process?

Accepted Answer

$$Q = W$$

Question 18

If the area under a PV curve is negative, what does this indicate about the process?

Accepted Answer

Work is done on the gas.

Question 19

A closed container of gas undergoes a process where the pressure decreases by half and the volume also decreases by half. What happens to the temperature?

Accepted Answer

It decreases by a factor of four.

Question 20

Which of the following is a correct statement about the sign convention for work in thermodynamics?

Accepted Answer

Work done by the gas is positive.

Ideal Gas Processes and PV Diagrams

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