Physics Units 1-4
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How do you calculate the amount of elastic potential energy stored in a spring?
E = ½ ke2
What happens to the gravitational potential energy of an object as it falls?
It changes to kinetic energy
What is specific heat capacity?
The energy required to raise the temperature of one kilogram of the substance by 10C
What is power?
Work done per unit time OR energy transferred per unit time
What is a power of one watt equal to?
1 J/s
What is the principle of conservation of energy?
Energy cannot be created or destroyed just transformed from one form into another
How could you reduce unwanted energy transfers in machinery with moving parts?
Oil/lubricate
How could you reduce unwanted energy transfer from a cup of coffee?
Insulate
Name 2 renewable energy resources available for use on earth.
Wind/wave/tidal/solar etc
Name 2 non-renewable energy resources available for use on earth.
Coal/oil/gas/nuclear
What is meant by a renewable energy resource?
Will not run out
What is electrical current?
Flow of charge/flow of electrons
What do you know about the current at any point in a series circuit?
It is the same
What happens to the resistance of an LDR as light intensity increases?
Decreases
What happens to the resistance of a thermistor as one temperature increases?
Decreases
Is mains electricity ac or dc?
a.c.
What is its frequency?
50Hz
What is its p.d?
230V
What is the difference between ac and dc?
a.c. - changes direction d.c. - one direction
What colour are the insulation coverings on live, neutral and earth wires?
live - brown, neutral - blue, earth - green & yellow
What is the earth wire there for?
As a safety device
What is the p.d. between the live wire and the earth?
230V
When does the earth wire carry a current?
If there is a fault
What are the 2 different equations to calculate power in an electrical circuit?
Power = IV Power = I2R