Physics Topic 3

What is the formula for density?

Density = Mass / Volume.

What is the standard unit used for density?

Kilograms per cubic metre.

What is internal energy?

The total kinetic energy and potential energy of all the particles inside a system.

What happens to the internal energy of a system when you heat it?

The internal energy increases.

What two things can happen when the internal energy of a system increases?

The temperature of the system rises, or it changes state.

What do you call a solid turning directly into a gas?

Sublimation.

Is a change of state a physical change or a chemical change?

A physical change (no new substances are made, and it can be reversed).

What happens to the mass of a substance when it changes state?

Mass is conserved (the mass stays exactly the same).

What happens to the temperature of a substance while it is changing state?

The temperature stays constant (stops changing).

What is the definition of Specific Latent Heat?

The amount of energy required to change the state of 1 kg of a substance with no change in temperature.

What is the formula linking energy, mass, and specific latent heat?

Energy = Mass multiplied by Specific Latent Heat.

What is the unit used for Specific Latent Heat?

Joules per kilogram (J/kg).

What is the Specific Latent Heat of Fusion?

The energy needed to change 1 kg of a substance from a solid to a liquid at its melting point.

What is the Specific Latent Heat of Vaporisation?

The energy needed to change 1 kg of a substance from a liquid to a gas at its boiling point.

What does a flat, horizontal line mean on a heating or cooling graph?

The substance is currently changing state.

What causes the temperature of a gas?

The average kinetic energy of its particles (faster particles mean a higher temperature).

What causes gas pressure inside a container?

Gas particles colliding with the walls of the container, exerting a force.

What happens to the pressure of a gas if you decrease its volume at a constant temperature?

The pressure increases.

What is the formula for gas pressure and volume changes?

Pressure multiplied by Volume = Constant.

Why does compressing a gas quickly cause its temperature to rise?

Work is done on the gas, which transfers energy to the kinetic store of the particles.