Quiz: Fundamentals of Thermal Energy and Heat Transfer — 10 perguntas

1. What is thermal energy primarily associated with in particles of a substance?

A. The average potential energy per particle

B. The total kinetic energy of particles

C. The average kinetic energy per particle

D. The total potential energy of particles

Answer: (B)

Explicação

Thermal energy is mainly related to the total kinetic energy of particles in a substance. It reflects how particles move and vibrate collectively, contributing to the substance's overall thermal energy.

2. What is the primary physical quantity that characterizes thermal energy in a substance?

A. The total kinetic energy of particles in the substance

B. The average potential energy of particles in the substance

C. The total energy including kinetic and potential energies

D. The temperature of the substance in Kelvin units

Answer: (A)

Explicação

Thermal energy refers to the total kinetic energy of all particles in a substance, not just the average or potential energy. Temperature, however, is related to the average kinetic energy per particle.

3. Which mode of heat transfer does not require a medium and depends on electromagnetic waves?

A. Evaporation

B. Convection

C. Radiation

D. Conduction

Answer: (C)

Explicação

Radiation transfers heat via electromagnetic waves and does not require a medium, unlike conduction and convection which need direct contact or fluid movement.

4. According to the revision sheet, what is the formula that relates the energy required to change temperature in a substance's specific heat capacity?

A. Q = mcΔT

B. Q = m/ c ΔT

C. Q = c/mΔT

D. Q = mc/ΔT

Answer: (A)

Explicação

The formula for heat energy involving specific heat capacity is Q = mcΔT, representing the energy needed to change the temperature of a mass m by ΔT.

5. During a phase change such as melting or boiling, what happens to the temperature of the substance while energy is still being added?

A. The temperature increases rapidly

B. The temperature remains constant

C. The temperature decreases

D. The temperature fluctuates

Answer: (B)

Explicação

During phase changes like melting or boiling, the temperature remains constant while latent heat is absorbed to change the phase, not to increase temperature.

6. Which law describes the power radiated by a body and states that it is proportional to the fourth power of its temperature?

A. Stefan-Boltzmann law

B. Fourier’s law

C. Newton’s law of cooling

D. Planck’s law

Answer: (A)

Explicação

The Stefan-Boltzmann law quantifies blackbody radiation, indicating that power radiated is proportional to T^4. Fourier’s law pertains to conduction, not radiation.

7. What does Fourier’s law govern in heat transfer?

A. Conduction of heat through a material

B. Heat transfer via electromagnetic waves

C. Heat transfer through fluid movement

D. Latent heat during phase change

Answer: (A)

Explicação

Fourier’s law describes conduction, where heat transfer occurs through direct contact influenced by thermal conductivity and temperature gradient.

8. What is the effect of heating materials in terms of thermal expansion as described in the sheet?

A. Materials expand; linear expansion is given by ΔL = α L₀ ΔT

B. Materials contract; linear expansion is given by ΔL = -α L₀ ΔT

C. Materials expand only in volume, not linearly

D. Materials do not change size; expansion only occurs in gases

Answer: (A)

Explicação

Heating causes materials to expand. The linear expansion formula is ΔL = α L₀ ΔT, indicating an increase in length proportional to temperature change.

9. Which of the following is NOT a mode of heat transfer as specified in the revision sheet?

A. Evaporation

B. Conduction

C. Convection

D. Radiation

Answer: (A)

Explicação

Evaporation is a phase change process and not a mode of heat transfer; the three primary modes are conduction, convection, and radiation.

10. What is the typical scale used to measure temperature in thermodynamics, as mentioned in the sheet?

A. Kelvin scale, where 0 K is absolute zero

B. Fahrenheit scale, with 32°F at freezing point of water

C. Rankine scale, based on Fahrenheit degrees

D. Reaumur scale, with 0° at freezing and 80° at boiling points of water

Answer: (A)

Explicação

The Kelvin scale is used in thermodynamics because 0 K (absolute zero) is the lowest possible temperature, and it is the SI base for thermodynamic temperature measurement.