P1 - Conservation And Dissipation Of Energy (PAPER 1) Flashcards
what are the 8 stores of energy
- Chemical energy
- Kinetic energy
- Gravitational Potential energy
- Elastic Potential energy
- Thermal energy
- Nuclear energy
- Magnetic energy
- Electrostatic energy
How can energy be transferred between stores?
By heating, Burning, Falling, Moving, Ascending
What is the Conservation of energy
Energy cannot be created or destroyed
What is a closed system
A system where no energy transfers take place out of or into the system’s energy stores
How do changes within a closed system work
Energy can be transferred between the energy stores of the system, but not to any other energy stores
What is WORK
Work is done on an object when a force makes it move
How are energy and work related
Work done = Energy transferred
What is the formula for work done by a force
Work done (J) = force applied (N) x distance moved along the line of action of the force
What happens to work done to overcome friction
Work done to overcome friction is transferred as energy to the thermal energy store of the objects that rub together and to the surroundings
What happens to gpe stores of an object when it moves up and down
Moving up - more gpe
Moving down - less gpe
Why does the gpe store of an object increase as it goes up
More work is done on it to overcome the gravitational energy
what is the formula for the change of gpe store
change of gravitational potential energy store (J) = mass (kg) x gravitational field strength (N/kg) x change of height (m)
why is it easier to lift an object on the moon than on the earth
because the gravitational field strength is lower on the moon than on the earth
what is the gravitational field strength on the earth
9.8 / 10
what does the amount of energy in a kinetic energy store depend on
the object’s speed and mass
what is the formula for the amount of energy in a kinetic energy store
kinetic energy (J) = 1/2 x mass (kg) x speed^2 (m/s)^2
what is the elastic potential energy store
it is the energy stored in an elastic when work is done on it
what is the formula for the amount of energy in an elastic potential energy store
elastic potential energy (J) = 1/2 x spring constant (N/m) x extension^2 (m)^2
what is useful energy
energy which is in the correct energy store that we want it in
what is wasted energy
energy that is transferred into an energy store that we don’t want it in
what happens to wasted energy
wasted energy eventually gets transferred to its surroundings as thermal energy
is wasted energy useful after it has dissipated
it becomes less and less useful as it dissipates
what does efficiency mean
how much useful energy is transferred
/
total energy supplied
what is the maximum efficiency a device can have
100%
what are 4 ways that machines waste energy
- friction
- air resistance
- electrical resistance
- noise
how is energy most commonly supplied to houses
- electricity
- gas
- oil
what does power mean
the rate of transfer of energy
what is the formula for the power of an appliance
power (W) = energy transferred (J) / time taken (s)
what is the formula for efficiency in terms of power
efficiency = useful power transferred / total power supplied x 100
what is the formula for the power wasted by an appliance
power wasted = total power supplied - useful power transferred
