P1-Conservation And Dissipation Of Energy Flashcards
(22 cards)
What are the 8 energy stores?
Thermal, kinetic, gravitational potential, elastic potential, nuclear, magnetic, chemical, and electrostatic
What are the 4 energy transfer pathways?
Mechanically, electrically, by heating, and by radiation (light of sound)
What is a system?
An object or a group of objects
Principle of conservation of energy
Energy cannot be created or destroyed
What is a closed system?
A system where neither matter nor energy can enter or leave
Energy transferred=
Work done
Ep=
mgh
Ek=
1/2 x m x v^2
Ee=
1/2 x k x e^2
Elastic potential energy=
1/2 x Spring constant x Extension^2
What is useful energy?
Energy transferred to where it is wanted in the way that it is wanted
What is wasted energy?
Energy that is not usefully transferred
What happens to energy as it dissipates?
It becomes less and less useful
What is the input energy?
The energy supplied to the device
What is the useful output energy?
The useful energy transferred by the device
Efficiency =
Useful output energy / total input energy
How can you reduce friction between moving parts?
Lubricate the moving parts
How can you reduce the energy wasted due to the resistance of a wire causing it to get hot?
Use wires with as little electrical resistance as possible
How can you reduce air resistance?
Streamline the shape of moving objects
How can you reduce energy wasted from the sound created by machinery?
Cut out noise (e.g. tighten loose parts to reduce vibration)
What is power?
The rate of energy transferred
Power =
Energy transferred / time taken
