P1 - Energy Stores and Transfers (PAPER 1) Flashcards
What are the 8 energy stores
kinetic, gpe, epe, thermal, chemical, nuclear, magnetic, electrostatic
What are the four ways in which energy can be transferred
heating, waves, electric current, mechanically (with forces)
What is a system
an object or group of object
What is a closed system
a system where no energy can be transferred to or from the surroundings - the total energy in the system stays the same
What is work done
energy transferred when a force moves an object
What is the unit for energy
Joules (J)
what is one joule of work
the work done when a force of 1N causes an object to move 1m in the direction of the force
What is the energy transfer when a moving car slows down
- mechanically from the kinetic store to the thermal store of the brakes
Some is dissipated to the thermal store of the surroundings
What is the energy transfer when an electric kettle is used to heat water
- electric current transfers energy to heating element’s thermal energy stores
energy is transferred by heating from the heating element’s thermal store to the water’s thermal store
What is the unit that represent one joule transferred per second
watt (W)
What is the energy transfer when a ball is fired using an elastic band
energy is transferred mechanically from the elastic store of the elastic band to the kinetic store of the band
some energy is dissipated to the thermal store of the surroundings
What are the two ways of reducing waste energy
- lubrication - reducing energy lost to friction
- streamlining - reducing energy wasted due to air resistance or drag
What is the law of conservation of energy
energy cannot be created or destroyed - only transferred usefully, stored or dissipated
What is efficiency
- what is the equation for efficiency as a decimal
- a measure of how much energy is transferred usefully
- useful energy output / total energy input
