Physics P3

• The amount of kinetic energy and potential energy of all the particles in the system
• A rise in temperature - particles speed up - gain kinetic energy
• Melts or boils - energy breaks bonds - increases potential energy

• The amount of energy needed to raise the temperature of 1kg of a substance by 1 degrees

change in thermal energy = mass x specific heat capacity x temperature change

SOLID

• strong forces of attraction
• held together in regular patterns
• not much energy - can only vibrate

LIQUID

• weaker forces of attraction
• close together - can move past each other
• some energy - random directions - low speeds

GAS

• no forces of attraction
• more energy - free to move
• random directions and speeds

• When particles collide, they exert a force called pressure
• In a sealed container - outward gas pressure = total force exerted by all the particles
• Increasing the temperature - energy transferred to kinetic energy stores - more collisions

• Density = measure of the 'compactness' of a substance

density = mass / volume

• Internal energy is the energy stored by the particles that make up a system

• Solid to Liquid = melting
• Liquid to Solid = freezing
• Liquid to Gas = boiling / evaporating
• Gas to Liquid = condensing
• Solid to Gas = sublimating

• The amount of energy needed to change 1kg of a substance from one state to another without changing its temperature

energy = mass x specific latent heat