Studied by 1 personWhat is the formula for working out kinetic energy?
Kinetic energy = ½ x mass x speed^2
What is the standard unit for mass?
Kilograms
What is the standard unit for speed?
m/s (meters per second)
What is the standard unit for kinetic energy?
Joules
What is the standard unit for elastic potential energy?
Joules
What is the standard unit for spring constant?
Newtons per metre (N/m)
What is the standard unit for extension in the elastic potential energy equation?
Metres
What is the formula for gravitational potential energy
G.P.E = mass x gravitational field strength x height
What is the standard unit for gravitational field strength?
N/kg (newtons per kilograms)
What is the standard unit for specific heat capacity?
Joules per kilogram per degree Celsius (J/KgoC)
What is this the definition of: The amount of energy required to raise the temperature of 1kg of a substance by 1oC
Specific Heat Capacity
What is defined as the rate at which energy is transferred or work is done?
Power
What is the standard unit for power?
Watts
What is the equation that links power, energy transferred and time?
Power =Energy transferred Time
What is the equation that links power, work done and time?
Power =Work Done Time
What is energy transferred the same as?
Work done
An energy transfer of 1 joule per second is equal to a power of?
1 Watt
If two electric motors both lift the same weight, the same height which will do it faster?
The more powerful one
Energy can be transferred, stored or dissipated but cannot be
Created or destroyed
In what type of system is there no net change to the total energy?
Closed
How can we reduce unwanted energy transfers?
Lubrication
Use of thermal insulation
How does increasing the thermal conductivity of a material affect the rate of energy transfer by conduction?
It increases it
What factors affect the rate of cooling of a building?
Thickness of walls
Thermal conductivity of walls
How do you work out efficiency from input and output energy?
Efficiency =Useful output energy transfer /Total input energy transfer
How do you work out efficiency from power input and output
Efficiency =Useful power output /Total power input
What are the three main types of fossil fuels?
Coal, Oil, Gas
Name the main non-renewable energy resources?
Fossil fuels, Nuclear fuel
Name 6 renewable energy resources
Biofuel, Wind, Hydro-electricity, Geothermal, Tidal, Solar, Water waves
What type of resource is one that is being replenished as it is used?
Renewable
What is required for an electrical charge to flow through a closed circuit?
A potential difference
What is the flow of electrical charge?
electrical current
What equation links charge flow, current and time?
Charge flow = Current x Time
What is the standard unit for current?
Amps
What is the standard unit for Charge flow?
Coulombs
What is the standard unit for time?
Seconds
What is the equation that links resistance, potential difference and current?
Potential difference = Current x Resistance
What two things does the current flowing through a component depend on?
Resistance Potential Difference
If you increase the resistance of a component what happens to the current, for a set potential difference
Decreases
What is the standard unit for resistance?
Ohms
What is the standard unit for potential difference?
Volts
How are current and potential difference linked in an ohmic conductor
They are directly proportional
Through which component is resistance constant?
Ohmic conductor
How does the resistance of a filament lamp change as the temperature increases?
It increases
How does the current flow in a diode?
only flows in one direction
What can you tell me about the resistance in a diode?
Very high in the reverse direction
How does the resistance of a thermistor change as the temperature increases?
It decreases
How does the resistance of an LDR change as light intensity increases?
It decreases
What could LDR's be used for
Switching lights on when it gets dark
What could a thermistor be used for?
In a thermostat to control heating
What is the current like in a series circuit?
the same everywhere
What is the total resistance of two components in a series circuit?
It is the sum of the resistance of each component
What is the total resistance of two resistors connected in parallel?
Less than the resistance of the smallest resistor
What type of supply is the mains electricity in the UK?
AC
What is the frequency of the domestic electricity supply in the UK?
50Hz
What is the voltage of the domestic electricity supply in the UK?
230V
What type of potential difference varies between a positive and negative value?
Alternating
What type of potential difference is only found in the positive?
Direct
How are most electrical appliances connected to the mains?
Using a three-cord cable
What colour is the live wire?
Brown
What colour is the neutral wire?
Blue
What colour is the earth wire?
Green and yellow stripes
What does the live wire carry?
The alternating potential difference from the supply
What does the neutral wire do in a plug?
Completes the circuit
What does the earth wire do in a plug?
It is a safety wire to stop an appliance becoming live
What is the potential difference between the live wire and the earth?
230V
What is the voltage of the neutral wire
At or close to 0V
What is the voltage of the earth wire
0V, unless there is a fault
What equation links power, potential difference and current?
Power = Potential difference x Current
What equation links current, resistance and power?
Power = (Current)2 x Resistance
What does the amount of energy an appliance transfers rely on?
How long the appliance is switched on for
The power of the appliance
What is done when charge flows in a circuit?
Work
What equation links energy transferred, power and time?
Energy transferred = Power x Time
What equation links charge flow, potential difference and energy transferred
Energy transferred = charge Flow x Potential Difference
What is the National Grid?
A system of cables and transformers linking power stations to consumers
What is transferred from power stations to consumers using the National Grid?
Electrical power
What are used to increase the potential difference from the power station to the transmission cables?
Step-up transformers
What are used to decrease the potential difference for domestic use in the National Grid?
Step- down transformers
What is the potential difference like in the transmission cables in the National Grid?
Very high
What is the equation to work out density?
density= mass/volume
Standard unit for density?
Kg/m³
When a substance changes state what happens to the mass?
It stays the same
Why is a physical change different from a chemical change?
In physical changes the material recovers its original properties if the change is reversed
What do we call the energy stored inside a system by the particles that make up the system?
Internal energy
What is the internal energy of a system made up of
The total kinetic and potential energy of all the particles
What effect does a change of state have on the overall temperature of a system?
None
What does the increase in temperature of a material depend on?
The mass of the substance
The type of material
The energy input into the system
What is the energy needed for a substance to change state called?
Latent heat
What is the amount of energy required to change the state of one kilogram of a substance with no change in temperature?
Specific Latent Heat
What can a gas do?
Compressed or expanded
What can a pressure produce?
A net force at right angles to the wall of the container (or any surface)
What is pressure measured in?
Pascals (Pa)
What is volume measured in?
m^3
What is the equation that links volume, pressure and constant, for a fixed mass of gas held at a constant temperature?
pressure × volume = constant
What is work the transfer of?
Energy by a force
What will work do to a gas?
Increase the internal energy and temperature
What is the unit for specific latent heat?
J/kg
What is the specific latent heat of fusion?
The change of state from solid to liquid
What is the specific latent heat of vaporisation?
The change of state from liquid to vapour
How do the particles in a gas move?
randomly
What is the temperature of a gas related to?
The average kinetic energy of the molecules
Note
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