Verified Questions & Answers | Revision
Pack | A+ Verified
• How is energy transferred? -✓✓1) Mechanically - force doing work
2) Electrically - work done by moving charges
3) Heating/Radiation - light, sound
• How can work be done? -✓✓When a current flows or by a force
moving an object
• What happens when an object falls and there's no air resistance? -
✓✓Energy lost from the g.p.e store = energy gained in the kinetic
energy store
• What does air resistance do when acting against falling objects? -
✓✓It causes some energy to be transferred to other energy stores e.g.
the thermal energy stores of the object and the surroundings
• What is SHC? -✓✓The amount of energy needed to raise the
temperature of 1kg of a substance by 1°C
• What is power? -✓✓The rate of energy transfer, or the rate of doing
work
,• What is 1W equal to? -✓✓1J of energy transferred per second
• What is conduction? -✓✓The process where vibrating particles
transfer energy to neighbouring particles
Energy is transferred to thermal stores of the object - this energy is
shared across the kinetic energy stores
• What is thermal conductivity? -✓✓A measure of how quickly energy
is transferred through a material via conduction
• What is convection? -✓✓Where energetic particles move away from
hotter to cooler regions
Energy is transferred to the thermal energy stores of the object and is
shared across the kinetic stores
• What do radiators create? -✓✓Convection currents
• Convection currents - process -✓✓1) Energy is transferred from the
radiator to the nearby air particles by conduction
2) The air by the radiator becomes warmer and less dense as the
particles move quicker
3) The warm air rises and displaces the cooler air, which is then heated
by the radiator
, 4) The previously heated air transfers energy to the surroundings - the
air cools, becomes denser and sinks
• Thermal insulation techniques -✓✓1) Cavity walls - made up of an
inner and outer wall with an air gap in the middle - the air gap reduces
the amount of energy transferred by conduction through the walls
2) Cavity wall insulators - the air gap is filled with foam also reduces
energy transfer by convection in the wall cavity
3) Loft insulation - reduces convection currents being created in lofts
4) Double-glazed windows - air gap between two sheets of glass that
prevent energy transfer by conduction through the windows
5) Draught excluders - reduce energy transfers by convection around
doors and windows
• How do you improve efficiency? -✓✓1) Lubrication
2) Insulation
3) Making objects more streamlined
• How do thick walls prevent energy losses through heating? -
✓✓They're made from a material with a low thermal conductivity - the
thicker the walls, the lower the thermal conductivity, the slower the
rate of energy transfer
• Fossil fuels (coal, oil, natural gas) -✓✓Non-renewable