Energy Flashcards
Give some examples of energy stores
Chemical, Kinetic, Gravitational, Thermal, Elastic, Magnetic, Electrostatic, Nuclear
What is the law of conservation of energy?
Energy can be transferred usefully, stored or dissipated, but cannot be created or destroyed
What are the units for energy?
J or Joules
What is the equation linking kinetic energy, mass and velocity?
Kinetic energy = 0.5 x mass x (speed)
When is energy stored in an elastic potential energy store?
An object has been deformed (stretched or compressed)
What is the equation linking elastic potential energy, the spring constant and extension?
elastic potential energy = 0.5 x spring constant x (extension)
When is energy stored in a gravitational potential energy store?
An object is raised above ground level
What is the equation linking gravitational potential energy, mass, gravity and height?
G.P.E = mass x gravitational field strength × height
When is energy stored in a chemical energy store?
Chemical bonds between molecules
When is energy stored in a thermal energy store?
An object is at a temperature above absolute zero (-273°C)
When is energy stored in a kinetic energy store?
An object is moving
What is specific heat capacity?
The amount of energy required to raise the temperature of one kilogram of the substance by one degree Celsius
What is the equation linking change in thermal energy, mass, specific heat capacity and change in temperature?
change in thermal energy = mass × specific heat capacity x temperature change
What is power?
The rate at which energy is transferred or the rate at which work is done
What is the equation linking power, energy and time?
Energy transferred = Power x time
What are the units of power?
W or watts
What is the equation linking power, work done and time?
power = work done ÷ time
What power is an energy transfer of 1 joule per second?
1 watt
What happens to wasted energy?
Dissipates to the surroundings
How can we reduce the amount of wasted energy? (HT ONLY)
Through lubrication and the use of thermal insulation
Give three examples of insulation that can be used in the house
double glazed windows, loft insulation, cavity wall insulation
What is the equation for working out efficiency?
efficiency = useful output energy transfer ÷ total input energy transfer
What does the thermal conductivity of a material tell us?
The rate of energy transfer by conduction
What are the main energy resources on Earth?
fossil fuels (coal, oil and gas), nuclear fuel, biofuel, wind, hydro-electricity, geothermal, the tides, the Sun and water waves
