Q: A student catches the flu and his body temperature increases from $$37.0^\circC to$$ $$39.0^\circC. If $$his mass is $$70 kg $$and the specific heat of the body is $$3400 J/kg K$$, how much energy is required for this temperature increase?

$$Q = (70)(3400)(2.0) = 4.8 \times 10^5$ J

Question 1

Which of the following best describes the first law of thermodynamics?

Accepted Answer

Energy cannot be created or destroyed, only transferred as work or heat.

Question 2

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

Accepted Answer

It increases.

Question 3

Which equation correctly expresses the first law of thermodynamics for a closed system?

Accepted Answer

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

Question 4

During an isochoric process, what is the work done on the gas?

Accepted Answer

$$W = 0$$

Question 5

A block is dragged across a rough surface and becomes warmer. The temperature increase occurs because of:

Accepted Answer

Work done on the block.

Question 6

For an isothermal compression of an ideal gas, which formula gives the work done on the gas?

Accepted Answer

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

Question 7

Two liquids, A and B, of equal mass and initial temperature are heated for the same time with identical burners. Afterward, liquid A is hotter than liquid B. Which has the larger specific heat?

Accepted Answer

Liquid B

Question 8

A 1 kg piece of silver ($$c = 234 	ext{ J/kg K}) at$$ $$100^\circC is $$placed in 1 kg of water ($$c = 4190 	ext{ J/kg K}) at$$ $$0^\circC in an $$insulated beaker. What is the final temperature?

Accepted Answer

Between $$0^\circC $$and $$50^\circC$$

Question 9

Which equation gives the amount of heat required to change the temperature of a mass $$M of a $$substance by $$\Delta T$$?

Accepted Answer

$$Q = Mc \Delta T$$

Question 10

Which process is characterized by a change in thermal energy without a change in temperature?

Accepted Answer

Phase change

Question 11

A gas is rapidly compressed in a cylinder, with no heat exchange with the environment. What type of process is this?

Accepted Answer

Adiabatic

Question 12

During an adiabatic expansion of a gas, what happens to its temperature?

Accepted Answer

It decreases.

Question 13

Which formula gives the rate of heat transfer by conduction through a material of area $$A$$, thickness $$L$$, and thermal conductivity $$k$$, with temperature difference $$\Delta T$$?

Accepted Answer

$$\frac{dQ}{dt} = \frac{kA \Delta T}{L}$$

Question 14

If the temperature of the sun suddenly dropped to half its present value, by what factor would its power output decrease?

Accepted Answer

1/16

Question 15

Which equation gives the net rate of heat transfer by radiation between an object of area $$A$$ and temperature $$T$$ and its environment at temperature $$T_{env}$$?

Accepted Answer

$$\frac{dQ}{dt} = e \sigma A (T^4$ - T_{env}^4)$$

Question 16

Which of the following statements about specific heats of gases is correct?

Accepted Answer

$$C_p = C_v + R$$

Question 17

A student catches the flu and his body temperature increases from $$37.0^\circC to$$ $$39.0^\circC. If $$his mass is $$70 kg $$and the specific heat of the body is $$3400 J/kg K$$, how much energy is required for this temperature increase?

Accepted Answer

$$Q = (70)(3400)(2.0) = 4.8 	imes 10^5$ J

Question 18

Which of the following mechanisms is NOT a way heat is transferred between a system and its environment?

Accepted Answer

Reflection

Question 19

A refrigerator uses the vaporization of Freon to cool the air. What physical principle is being exploited?

Accepted Answer

The heat of vaporization

Work, Heat, and the First Law of Thermodynamics – Chapter 19 Study Notes

Guida di studio - Domande di pratica

Study guide - Flashcard