# Physics P1 Unit 1

• Created by: ola_k12
• Created on: 07-06-16 15:36
• P1 Unit 1  Energy transfer by heating
• Light, shiny surfaces absorb less radiation than dark, matt surfaces
• Light, shiny surfaces reflect more infrared radiation than dark matt surfaces
• 1.3 States of matter
• Solid particles are held next to each other in fixed positions
• Have a fixed shape
• Liquid particles move at random but are in contact with eachother
• Takes shape of a container that it is in and can flow
• Gas particles move about randomly and are much further apart
• No fixed volume
• 1.4 Conduction
• Metals conduct energy better than non-metals
• Metals contain free electrons
• Electrons move about at random inside a metal and hold the positive ions together
• Ions - an atom or molecule with an electric charge due to the loss or gain of one or more electrons
• When a metal is heated electrons spread out and collide with free electrons and ions in the cooler parts of the metal
• As a result, the electrons transfer kinetic energy to these electrons and ions
• In non-metals, the electrons are held in the atoms
• Energy only occurs when atoms vibrate and shake each other. That's why non-metals are good conductors
• 1.5 Convection
• Circulation of a gas or fluid caused by heating it
• Heat makes liquid or gas less dense which causes circulation
• 1.6 Evaporation and condensation
• Evaporation is when a liquid turns to gas
• Faster moving molecules are escaping from the liquid
• Evaporation can be increased by increasing the surface area of the liquid and increasing it's temperature
• Condensation is when gas turns into a liquid
• Condensation can be increased the area of the surface or reducing the temperature of the surface
• 1.7 Energy transfer by design
• The rate of energy transferred to or from an object depends on:
• The materials that the object is in contact with
• The temperature difference between the object and its surroundings
• 1.8 Specific heat capacity
• Change of temperature: E =  m × c × theta
• c = E ÷ m × theta
• The greater the mass of an object, the more slowly its temperature increases when heated
• Rate of temperature change of a substance depends on:
• Energy supplied to it
• Its mass
• Its specific heat capacity
• 1.9  Heating and insulating buildings
• U-values tell us how much energy per second passes through different materials
• Energy transfer from our homes can be reduced by fitting:
• Loft insulation
• Cavity wall insulation
• Double glazing
• Draught proofing