P1 Energy

Created by

Erin Dovey

Cards (42)

List the 8 energy stores:
Thermal
Kinetic
Gravitational potential
Elastic potential
Chemical
Magnetic
Electrostatic
Nuclear
Which 4 ways can energy be transferred?
Mechanically
Electrically
Heating
Radiation
When we talk about energy, what is. system?
An object or group of objects involved in the energy transfer
What happens to energy when a system changes?
Energy is transferred
What is a closed system?
A system where energy cannot enter or leave
What might be a better way of describing wasted energy? energy that is stored in a less useful way
What is work done?
another way of saying: energy transferred
How does throwing a ball 'do work'?
Chemical energy store in a persons arm is transferred to kinetic energy store in the persons arm and the ball
How does dropping a ball do work?
Gravitational potential energy store in ball is transferred to kinetic energy store
How do the brakes on a car do work?
Friction between the cars brakes and the wheels transfers kinetic energy store into a thermal energy store
What happens if you do work against frictional forces on an object?
The temperature of the object rises
Describe how work is done during a collision?
The cars kinetic energy store is transferred into elastic potential and thermal energy stores in the car
How does boiling a kettle do work?
The energy is transferred to the waters thermal energy store by heating
Formula for kinetic energy?
0.5 x mass x (velocity)^2
Formula for elastic potential energy?
0.5 x spring constant x (extension)^2
What does the formula for elastic potential energy assume about the object?
The limit of proportionality has not been exceeded
definition of gravitational potential energy?
amount of energy gained by an object raised above ground level
formula for calculating gravitational potential energy?
mass x gfs x height
what is meant by the specific heat capacity of a substance?
the amount of energy required to raise the temperature of 1kg of the substance by 1 degree
what is the equation linking energy transferred to specific heat capacity?
mass x specific heat capacity x temperature change
definition for power?
rate at which energy is transferred
rate at which work is done
2 formulae for calculating power?
power = energy transferred / time
power = work done / time
what is the unit for power?
watts
What is the watt equivalent to?
1 watt = 1 joule
What is conservation of energy?
Energy can be:
transferred usefully
stored or dissipated
but can never be created or destroyed
Describe the energy transferred by a mobile phone?
Energy is usefully transferred from the chemical energy of the battery
But some energy is dissipated(wasted) as thermal energy
2 ways of reducing unwanted energy transfers:
lubrication
thermal insulation
How does lubrication reduce wasted energy transfer?
Reduces friction.
How does insulation reduce wasted energy transfer?
prevents thermal energy loss to the surroundings
How is thermal energy transferred through solid materials?
Conduction
How is thermal energy transferred through a liquid or gas?
convection
What is thermal conductivity a measure of?
How quickly energy is transferred through a material by conduction
What affects the rate of cooling of a building?
thickness of walls
thermal conductivity of walls
What is the formula for calculating efficiency of energy transfers?
Efficiency = Useful energy output / Total energy input
List 2 ways to increase efficiency of energy transfer?
Increase useful energy output
Decrease wasted energy output
Why is useful energy output not equal to total energy output?
some energy is usually transferred to wasted thermal energy
What is meant by a non-renewable energy resource?
An energy source that will eventually run out
What are 3 types of fossil fuels?
Crude oil, natural gas and coal
Fossil fuels are non-renewable
Name the other non-renewable energy resource?
Nuclear energy
What is meant by a renewable energy resource?
These sources can be renewed as they are being used and will not run out