Energy (P1) Flashcards
Name the ten energy forms
Magnetic Kinetic Heat Light Gravitational potential Chemical Sound Electrical Elastic potential Nuclear
What does conservation of energy mean?
No energy is ever created or destroyed.
It can be released if it is an open system but not if it’s closed
What is work done
Energy transferred=work done
Work done (J)= Force (N) x Distance(m) Energy transferred= power x time
Weight equation
Weight (N) = Mass x gravitational field strength
Efficiency
Useful energy transferred by device
———————————————- x 100
Total energy transferred by device
Gravitational potential energy equation
GPE= mass x gravitational field strength x height
J=kg x N/kg x m
Kinetic energy equation
Kinetic energy = half x mass x velocity squared
J= kg x m/s
What is power?
How quickly energy is transferred from one form to another
Power (W) = energy transferred (J) / time (s)
Hooke’s law
Force applied to a spring= spring constant X extension
Equation for change in thermal energy
Mass x SHC x temperature change
Elastic potential equation
0.5 x spring constant x acceleration2
Power equation
Power = work done/time
What are the 4 energy pathways?
Thermal
Mechanical
Radiation
Electrical
Internal energy
The total kinetic and potential energy of particles in an object
Potential energy
Energy that is stored with the potential to do work
8 energy stores
Thermal Kinetic Gravitational potential Elastic potential Chemical Magnetic Electrostatic Nuclear
How can energy be transferred
Heating or doing work
Energy transfers when falling
GPE to kinetic
SHC
The energy required to increase the temperature of 1kg of a substance by 1 degree
Change in thermal energy
Mass x SHC x temperature change
Conduction
Where vibrating particles transfer energy to neighbouring particles
Convection
Where energetic particles move away from hotter to cooler regions
Radiators
Conduction transfers energy from the radiator to nearby air particles
Air becomes warmer and less dense
Warm air rises and is replaced by cooler air
The cycle repeats as it rises, then cools and falls to be heated again
Lubrication
Reduces frictional force by reducing the friction between surfaces when they move
Cavity wall insulation
Made up of an inner or outer wall with an air gap in the middle, reduces the energy transferred by conduction
Cavity wall insulation has foam to reduce convection
Loft insulation
Reduces convection currents produced in lofts
Double-glazed windows
Double-glazed windows have an air gap between windows to reduce conduction through the windows
Drought excluders
Reduce energy transfers by convection
Payback time equation
Cost of installation / energy saving costs
