physics 1.4 yr11 PAGE 2

Define heat

Heat is the energy that is transferred when an objects temperature changes.

What is heat?

The energy transferred when the internal energy of a body changes

What is temperature?

A measure of the average kinetic energy due to the motion of particles in a substance

How is temperature related to the kinetic energy of particles in a substance?

Temperature is a measure of average kinetic energy of the particles. Higher temperature means particles have more average kinetic energy and move faster.

What is thermal equilibrium and how is it reached?

Heat energy is transferred from a hotter object to a cooler one until both reach the same temperature. At this point, there is no net heat transfer, and thermal equilibrium is reached.

Define thermal expansion

The increase in size (volume or length) of a substance when it is heated

What are everyday examples of thermal expansion?

Examples of thermal expansion include railway tracks having small gaps, bridges using expansion joints, and power lines sagging more in hot weather.

How does a change in particle motion cause a change in the volume of an object?

When a substance is heated, its particles gain kinetic energy and move faster. This increases the space between particles, causing the substance to expand. When cooled, particles lose kinetic energym move less and come closer together, so the volume decreases.

Describe heat energy in terms of kinetic theory

Heat energy is the total kinetic energy of the randomly moving particles in a substance. When heat is added, particles gain kinetic energy and move faster; when heat is removed, they lose kinetic energy and move more slowly.

How does particle motion transfer heat energy through a substance?

Heat energy is transferred through a substance by particles vibrating and colliding with neighbouring particles. These collisions pass on kinetic energy from faster moving particles to slower moving particles, carrying energy through the object.

What is specific heat capacity?

The amount of heat energy required to raise the temperature of a 1kg substance by 1K or 1C

How does specific heat capacity affect the amount of heat energy needed to change a substance’s temperature?

The higher a substance’s heat capacity, the more heat energy is needed to change its temperature by a given amount. A lower specific heat capacity means less energy is needed.

Why is specific heat capacity of different substances important?

Specific heat capacity determines how quickly a substance heats up or cools down.

How does a substance’s specific heat capacity affect how easily its temperature changes?

Substances with a high specific heat capacity need more energy to change temperature, while substances with a low specific heat capacity need less energy and change temperature more easily.

Why is the E=mcAT used?

To calculate the amount of heat energy gained or lost when a substance changes temperature

What are the units of specific heat capacity?

Joules per kilogram per kelvin

Explain heat transfer by conduction and what state of matter is it most effective in?

Conduction transfers heat through a substance when particles collide with neighbouring particles, passing on kinetic energy from hotter reigions to cooler regions. Conduction is most effective in solids and metals because particles are close together.

What is the difference between conductors and insulators?

Conductors allow heat energy to pass through them easily, while insulators slow down or resist the transfer of heat energy.

What happens to particles when an object is heated?

Temperature increases, particles gain kinetic energy and vibrate or move faster, spreading further apart

How is heat transferred by convection?

Heat is transferred by the movement of warmer, less dense fluid to cooler areas.

In which states of matter does convection occur?

Convection occurs in liquids and gasses (fluid)

What is a convection current?

A circular movement of fluid caused by warm, less dense fluid rising and cool, denser fluid sinking.

How is heat transferred by radiation?

By infared radiation (electromagnetic waves) without needing particles.

What is radiation?

Radiation is heat energy in the form of infared light that can travel through a vacuum.

What is emission?

The release of infared radiation from an object

What is absorbtion?

The taking in of infared radiation by an object.

What is a vacuum?

A space with no particles or matter present.

How does particle motion transfer heat energy through a substance?

Particles transfer kinetic energy through collisions, moving heat from hotter areas to cooler areas.

How do particle movements in a liquid or gas cause changes in density?

When particles are heated, they move faster and spread further apart, making the fluid less dense. Cooling causes particles to move slower and come closer together, making it denser.

How do changes in density create convection currents?

Warm, less dense fluid rises while cool, denser fluid sinks, creating a continuous circulation called a convection current.

How are temperature changes related to the emission and absorbtion of radiation?

Objects absorb radiation and warm up, or emit radiation and cool down.

How do the colours black, white, and silver affect the absorption and emission of infrared radiation

Black surfaces are good absorbers and emitters of infrared radiation, while white and shiny silver surfaces are poor absorbers and emitters.

How can conduction, convection, and radiation transfer energy in a house heated by a fireplace?

Conduction transfers heat through solid objects, convection circulates warm air around the room, and radiation transfers heat directly from the fire as infrared waves.