Q: Which of the following best describes the 1st Law of Thermodynamics for a closed system?

$$\Delta E = W_{\text{on system}} + Q_{\text{gained}}$$

Question 1

Which of the following best describes the 1st Law of Thermodynamics for a closed system?

Accepted Answer

$$\Delta E = W_{	ext{on system}} + Q_{	ext{gained}}$$

Question 2

Two boxes, A and B, contain the same type of ideal gas at the same temperature, but Box A has more gas (greater mass) than Box B. Which statement is correct?

Accepted Answer

The gases in both boxes have the same average kinetic energy per molecule, but Box A has greater thermal energy.

Question 3

Which equation correctly relates pressure to force and area?

Accepted Answer

$$P = \frac{F}{A}$$

Question 4

The temperature of a gas is a measure of which physical quantity?

Accepted Answer

The average kinetic energy of each molecule: $$\frac{1}{2} m v^2$ = \frac{3}{2} k_B T$$

Question 5

A gas in a closed container has its thermal energy increased by 400 J as a result of 100 J of work being done on the system. How much heat must be transferred to the system?

Accepted Answer

300 J

Question 6

A gas in a closed container has its thermal energy decreased by 200 J as a result of 500 J of work being done on the system. How much heat must be transferred to the system?

Accepted Answer

-700 J

Question 7

A gas in a sealed container is heated by 500 J, but the internal energy does not increase. What must also be happening?

Accepted Answer

The gas is doing 500 J of work on its surroundings.

Question 8

A small amount of air is rapidly compressed in a closed syringe so that negligible heat can flow in or out. What happens to the temperature of the gas?

Accepted Answer

The temperature increases.

Question 9

Which of the following is a correct statement about the energy transformations in the human body according to the 1st Law of Thermodynamics?

Accepted Answer

Chemical energy from food is converted into work and heat, which are transferred to the surroundings.

Question 10

Which of the following equations represents the ideal gas law as commonly written in physics?

Accepted Answer

$$PV = N k_B T$$

Question 11

When the temperature of an ideal gas is raised from $$T_1 to$$ $$T_2 at $$constant volume, a positive amount of heat $$Q_v$$ flows into the gas. If the temperature is raised from $$T_1 to$$ $$T_2 at $$constant pressure, the amount of heat that flows into the gas is:

Accepted Answer

Greater than $$Q_v$$

Question 12

Which of the following is true about the work done on a gas in a piston?

Accepted Answer

Work is done on the gas when the piston compresses the gas, increasing its internal energy.

Question 13

The total thermal energy of a sample of gas is given by which equation?

Accepted Answer

$$E_{th} = \frac{3}{2} N k_B T$$

Question 14

In the context of the human body, which molecule is primarily used to store and release energy for muscle contraction?

Accepted Answer

Adenosine triphosphate (ATP)

Question 15

If the temperature of a gas in a closed syringe increases, which of the following must be true?

Accepted Answer

Heat is transferred into the system or work is done on the system.

Question 16

Which of the following best describes the difference between the physics and chemistry versions of the ideal gas law?

Accepted Answer

Physics uses $$PV = N k_B T$$ while chemistry uses $$PV = nRT.$$

Question 17

A person walks at constant speed on flat ground. According to the 1st Law of Thermodynamics, what happens to the chemical energy from food?

Accepted Answer

It is converted into kinetic energy, heat, and work done on the surroundings.

Question 18

Which of the following is a correct form of the 1st Law of Thermodynamics as written in chemistry?

Accepted Answer

$$\Delta U = q + w$$

Question 19

During rapid compression of a gas in a closed syringe, why does the temperature increase?

Accepted Answer

Work is done on the gas, increasing its internal energy since little heat escapes.

The First Law of Thermodynamics: Concepts, Applications, and Practice Problems

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