P1 Flashcards
Gravitational potential energy
Energy store
Maximum kinetic energy
Energy transfer
How does conservation of energy work?
- Maximum gravitational potential energy
- Maximum kinetic energy
- Maximum gravitational potential energy
- Then does the same the opposite way
What is the principle of conservation of energy?
Energy cannot be destroyed or created
What is work done
To move an object with an applied force
Formula for work done
Work done(j) = force(n) x distance(m)
Gravitational potential energy
The energy that a body has due to its height above the ground
Formula for change in gravitational potential energy
Change in gravitational potential energy = mass x gravitational field strength x change in height
What are the energy stores?
Chemical - batteries
Kinetic - moving object
Gravitational - due to position of object
Elastic - stretched or compressed spring
Thermal - warm object
Magnetic - attract/repelling
Electrostatic - two charges repelling or attracting
Nuclear - through radioactive decay
Energy transfers
Mechanical - when a force moves through a distance
Electrical
By heating - temperature difference
By radiation - microwaves, sound
Efficiency
The amount of input energy that is transferred to useful energy for a device
Formula for efficiency
Percentage efficiency = useful output divided by total imput x 100%
What is power
The amount of work done per second
Formula for power
Power = work done divided by time
What is the unit of power
Watts
Kinetic energy eqation
Kinetic energy(j) = 1/2 x mass x speed
Elastic potential energy equation
Elastic potential energy = 1/2 x spring constant x extension
Whats the highest efficiency percentage?
100%
What is useful energy
Energy transferred to where it is wanted in the way it is wanted
What is wasted energy
Energy that is not usefully transferred
Where does the wasted energy go?
It is eventually transferred to the surroundings, making it warmer
What happens after the energy is dissipated?
It gets less and less useful
