Thermal Energy Transfer and Equilibrium - AP Physics 2

State the formula for calculating the change in temperature.

$\triangle T = \frac{Q}{mc}$ . Rearranged form of $Q = mc\triangle T$ solving for temperature change.
Identify the unit of specific heat capacity.

Joules per kilogram per degree Celsius (J/kg·°C). Standard SI unit for specific heat capacity.
Choose the correct statement: Conduction occurs in fluids or solids?

Conduction occurs primarily in solids. Conduction requires direct particle contact in solid materials.
What is the formula for heat transfer by conduction?

$Q = \frac{kA(T_2 - T_1)t}{d}$ . Fourier's law where k is conductivity, A is area, d is thickness.
What does emissivity measure?

Emissivity measures how effectively a surface emits thermal radiation. Ranges from 0 to 1, with 1 being a perfect emitter.
Which process is used in thermal insulation?

Reducing heat transfer through conduction, convection, and radiation. Insulation blocks all three modes of heat transfer.
Identify the primary mode of heat transfer in solids.

Conduction. Direct contact between particles enables heat transfer.
What property measures how well a material conducts heat?

Thermal conductivity. Higher values indicate better heat conduction ability.
What does the Stefan-Boltzmann law describe?

The power radiated from a black body in terms of its temperature. Power is proportional to the fourth power of temperature.
Which process involves heat transfer by fluid motion?

Convection. Heat transfer occurs through bulk movement of fluids.
Identify the process of heat transfer without any medium.

Radiation. Electromagnetic waves carry energy through vacuum or space.
What is described by Newton's Law of Cooling?

The rate of heat loss of a body is proportional to the temperature difference with its surroundings. Describes exponential cooling behavior of heated objects.
What happens to energy during a phase change?

Energy is absorbed or released without changing temperature. Latent heat causes phase transitions at constant temperature.
What is the role of a heat sink?

A device that absorbs and dissipates heat from another object. Conducts heat away from components to prevent overheating.
Find the error: Heat flows from cold to hot spontaneously.

Correct: Heat flows from hot to cold spontaneously. Heat naturally flows from higher to lower temperature regions.
What is thermal expansion?

Increase in volume of a substance due to heat. Materials expand when heated due to increased molecular motion.
Find the error: Insulation is primarily used to conduct heat.

Correct: Insulation is used to reduce heat transfer. Insulation reduces, not increases, heat transfer rates.
What is the unit of latent heat?

Joules per kilogram (J/kg). Energy per unit mass for phase change processes.
Identify the factor that affects radiation heat transfer.

Surface area, temperature, and emissivity. All three factors determine the rate of radiant heat transfer.
What is the purpose of a thermal insulator?

To reduce the rate of heat transfer. Insulators minimize heat flow between different temperature regions.
Define specific heat capacity.

The amount of heat required to change the temperature of 1 kg of a substance by 1°C. This is the definition of specific heat capacity.
What is the significance of a high thermal conductivity material?

It transfers heat efficiently. Good conductors allow rapid heat flow between objects.
What is Fourier's Law of Heat Conduction?

Heat flux is proportional to the negative gradient of temperature. Heat flow rate is proportional to temperature gradient.
State the unit of thermal conductivity.

Watts per meter per Kelvin (W/m·K). SI unit for thermal conductivity in the fundamental units.
State the formula for latent heat.

$Q = mL$ . Where L is the latent heat per unit mass.
What is the principle of conservation of energy in thermal processes?

Energy cannot be created or destroyed; it is transferred or changed in form. First Law of Thermodynamics applied to thermal systems.
What condition defines a black body in thermal radiation?

Perfectly absorbs all incident radiation. Ideal absorber with emissivity equal to 1.
What is the formula for calculating thermal energy transfer?

$Q = mc\triangle T$ . Where Q is heat, m is mass, c is specific heat, and $\triangle T$ is temperature change.
State the relation between thermal conductivity and insulation.

Lower thermal conductivity means better insulation. Poor conductors prevent heat flow, making good insulators.
What is the heat transfer mode involved in a thermos flask?

Minimizes conduction, convection, and radiation. Vacuum and reflective surfaces block heat transfer mechanisms.
Choose the correct term: Heat or Temperature is a measure of energy transfer.

Heat. Heat is energy in transit, temperature measures thermal state.
Identify a factor that affects thermal expansion.

Material type and temperature change. Coefficient of expansion varies by material and temperature range.
What is thermal equilibrium?

It is the state when two objects in thermal contact no longer exchange heat. Both objects reach the same temperature at equilibrium.
What does a calorimeter measure?

The amount of heat transferred in a chemical reaction or physical process. Device for measuring heat changes in chemical or physical processes.
Which law states energy is conserved in thermal processes?

First Law of Thermodynamics. Conservation of energy principle in thermodynamic systems.

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