GCSE AQA Physics P3

State the equation for density

Density = mass / volume

What is the unit for density?

Kilograms per cubic metre (kg/m^3) or grams per cubic centimetre (g/cm^3)

Why are solids generally denser than liquids and gases?

Particles in a solid are tightly packed together in a fixed lattice with very little space between them

Why do gases have very low densities?

Particles in a gas are spread far apart with large empty spaces between them

How do you measure the density of a regular solid object?

Measure mass using a digital balance, measure dimensions with a ruler or vernier caliper to calculate volume, then use density = mass / volume

How do you measure the volume of an irregular solid object?

Submerge it in a Eureka (displacement) can filled with water up to the spout and measure the volume of displaced water

What instrument is used to collect and measure the displaced water in the density practical?

A measuring cylinder

How should you read the volume of liquid in a measuring cylinder to avoid parallax error?

Read the measurement at eye level from the bottom of the meniscus

How do you measure the density of a liquid?

Place an empty measuring cylinder on a balance and zero it, pour in a known volume of liquid, record mass, and calculate density = mass / volume

What is a physical change of state?

A change that alters the physical form without altering chemical composition, making it completely reversible and conserving mass

Name the change of state from solid directly to gas

Sublimation

What is internal energy?

The total kinetic energy and potential energy of all the particles that make up a system

What type of energy store in particles increases when a substance is heated and changes temperature?

Kinetic energy

What type of energy store in particles increases when a substance undergoes a change of state?

Potential energy

How does heating affect the internal energy of a system?

It increases the internal energy by increasing particle kinetic energy or increasing particle potential energy

What is specific heat capacity?

The amount of energy required to raise the temperature of 1 kg of a substance by 1 degree Celsius

What is specific latent heat?

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

State the equation linking energy, mass and specific latent heat

Energy = mass x specific latent heat

What is the unit for specific latent heat?

Joules per kilogram (J/kg)

What is specific latent heat of fusion?

The energy required to change 1 kg of a substance from solid to liquid at its melting point without changing temperature

What is specific latent heat of vaporisation?

The energy required to change 1 kg of a substance from liquid to gas at its boiling point without changing temperature

Why does temperature remain constant on a heating curve during a change of state?

Energy supplied breaks intermolecular forces (increasing potential energy) rather than increasing particle speed (kinetic energy)

How is the temperature of a gas related to the kinetic energy of its particles?

Temperature is directly proportional to the average kinetic energy of gas particles

How do gas particles exert pressure on the walls of a container?

Gas particles collide with container walls, exerting a force per unit area

How does increasing temperature affect gas pressure at constant volume?

Particles move faster and collide more frequently and forcefully with container walls, increasing pressure

How does increasing volume affect gas pressure at constant temperature?

Volume increases, spreading particles out, reducing the frequency of collisions per unit area and lowering pressure

State the equation for a fixed mass of gas at constant temperature

Pressure x volume = constant (p1 x V1 = p2 x V2)

What is the relationship between gas pressure and volume at constant temperature?

They are inversely proportional (if volume halves, pressure doubles)

What happens to a gas when work is done on it by compression?

Energy is transferred to the gas, increasing its internal energy and raising its temperature

Why does using a bicycle pump to inflate a tyre cause the pump to warm up?

Work is done on the gas as it is compressed, transferring energy to the kinetic store of the gas particles and increasing temperature

What happens to the pressure of a gas if it expands at constant temperature?

Pressure decreases because particles collide less frequently with the container walls