Q: Convert a temperature of 25°C to Fahrenheit using the correct formula.

$$T_F = \frac{9}{5}T_C + 32 = \frac{9}{5} \times 25 + 32 = 77$$^{\circ}$$F$$

Q: A steel rod of length $$L_0 = 2.0$$\ m$$ is heated from 20$$^{\circ}$$C to$$ $$120^{\circ}C$. Given the coefficient of linear expansion for steel is $$\alpha = 1.2 \times $$10^{-5}$$\ $$K^{-1}$$, what is the change in length $$\Delta L$$?

$$\Delta L = \alpha L_0$ \Delta T = 1.2 \times 10$$^{-5}$$ \times 2.0 \times (120 - 20) = 0.0024\ m$$

Q: Calculate the amount of heat required to raise the temperature of $$0.5\ kg of $$water from $$20^{\circ}C$ to 80$$^{\circ}$$C. ($$Specific heat of water $$c = 4190\ J/kg\cdot K)$$

$$Q = mc\Delta T = 0.5 \times 4190 \times (80 - 20) = 125,700\ J$$

Question 1

Which statement best describes thermal equilibrium?

Accepted Answer

Two systems are in thermal equilibrium if they have the same temperature.

Question 2

A thermometer measures temperature by detecting changes in which physical property?

Accepted Answer

The volume of the liquid inside the thermometer.

Question 3

According to the zeroth law of thermodynamics, if system A is in thermal equilibrium with system C, and system B is also in thermal equilibrium with system C, what can be concluded?

Accepted Answer

System A and system B must be in thermal equilibrium with each other.

Question 4

Convert a temperature of 25°C to Fahrenheit using the correct formula.

Accepted Answer

$$T_F = \frac{9}{5}T_C + 32 = \frac{9}{5} 	imes 25 + 32 = 77$$^{\circ}$$F$$

Question 5

What is the temperature in Kelvin when the Celsius temperature is -50°C?

Accepted Answer

$$T_K = T_C + 273.15 = -50 + 273.15 = 223.15\ K$$

Question 6

A steel rod of length $$L_0 = 2.0$$\ m$$ is heated from 20$$^{\circ}$$C to$$ $$120^{\circ}C$. Given the coefficient of linear expansion for steel is $$\alpha = 1.2 	imes $$10^{-5}$$\ $$K^{-1}$$, what is the change in length $$\Delta L$$?

Accepted Answer

$$\Delta L = \alpha L_0$ \Delta T = 1.2 	imes 10$$^{-5}$$ 	imes 2.0 	imes (120 - 20) = 0.0024\ m$$

Question 7

If a metal plate with a circular hole is heated, what happens to the diameter of the hole?

Accepted Answer

The diameter of the hole increases.

Question 8

Which material has the lowest coefficient of linear expansion according to the provided table?

Accepted Answer

Quartz (fused)

Question 9

Why do lakes freeze from the top down instead of from the bottom up?

Accepted Answer

Water decreases in volume as temperature increases between $$0^{\circ}C$ and 4$$^{\circ}$$C$$, causing denser water to sink and less dense ice to form on top.

Question 10

A bridge is constructed with expansion joints. What is the primary reason for including these joints?

Accepted Answer

To accommodate changes in length due to thermal expansion and prevent thermal stress.

Question 11

Calculate the amount of heat required to raise the temperature of $$0.5\ kg of $$water from $$20^{\circ}C$ to 80$$^{\circ}$$C. ($$Specific heat of water $$c = 4190\ J/kg\cdot K)$$

Accepted Answer

$$Q = mc\Delta T = 0.5 	imes 4190 	imes (80 - 20) = 125,700\ J$$

Question 12

Which of the following best describes the difference between specific heat and molar heat capacity?

Accepted Answer

Specific heat is the heat required to raise the temperature of one gram of a substance by one degree, while molar heat capacity is for one mole.

Question 13

During a phase change, such as melting or boiling, what happens to the temperature of the substance?

Accepted Answer

The temperature remains constant.

Question 14

A $$0.02\ kg$$ sample of gallium at $$29.8^{\circ}C$ is melted. If the heat of fusion is L_f = 8.04$$ 	imes $$10^4$$\ J/kg$$, how much heat is required?

Accepted Answer

$$Q = mL_f = 0.02 	imes 8.04 	imes 10^4$ = 1,608\ J$$

Question 15

Which mechanism of heat transfer does NOT require matter to be present between the objects?

Accepted Answer

Radiation

Question 16

A copper rod ($$k = 385\ W/m\cdot K) of $$length $$L = 0.5\ m$$ and cross-sectional area $$A = 0.001\ m^2$ has its ends maintained at T_H$$ = $$100^{\circ}C$ and T_C$$ = $$20^{\circ}C$. What is the rate of heat transfer through the rod?

Accepted Answer

$$H = kA \frac{T_H - T_C}{L} = 385 	imes 0.001 	imes \frac{100 - 20}{0.5} = 61.6\ W$$

Question 17

Which of the following substances is the best thermal insulator based on its thermal conductivity?

Accepted Answer

Styrofoam

Question 18

The Stefan-Boltzmann law for the heat current due to radiation is given by which formula?

Accepted Answer

$$H = \lambda \epsilon \sigma T^4$

Question 19

How do CO$$_2$$ molecules in the atmosphere contribute to climate change according to the study materials?

Accepted Answer

They absorb infrared radiation and reradiate part of it back toward the Earth's surface.

Chapter 17: Temperature and Heat – Structured Study Notes

Study Guide - Practice Questions

Study Guide - Flashcards