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Physics Unit 1 Revision

Energy
There are 9 different forms of energy:
Light Heat Chemical Kinetic (movement) Electrical
Elastic (Gravitational) potential Nuclear Sound

Energy is never created or destroyed! Energy is transferred from one form to
another form. Not all of the energy transferred by a device is useful energy.…

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The closer the efficiency is to 1 the more useful energy the device is transferring.
So for the light bulb example we got an efficiency of 0.1, so the light bulb isn't
very good and transferring useful energy.

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Kinetic theory
Most matter or substances can be classed as being solids, liquids or gases.
Solids: They have the least amount of energy are
arranged in a pattern. They vibrate around fixed
positions




Liquids: The particles are closely packed together but
can move about freely over one another.


Gases: They…

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escape from the surface of the liquid and enter the air. This makes the average
kinetic energy of the remaining particles less and the temperature goes down.


Condensation is when a liquid turns to a gas, like water forming on a cold window.
The rate of condensation can be increased…

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You can prevent heat loss from objects by using insulation. Air and other gases
are bad conductors of heat but make good insulators. For convection you must
stop the heat from rising e.g. using a lid.

Trapped air helps to prevent heat loss by conduction and convection. A vacuum
(empty…

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Specific heat capacity

Specific heat capacity is the amount of energy needed to raise the temperature
of a 1 kilogram substance by 1°C. If an object has a low specific heat capacity
then it is quick to heat up, if it has a large specific heat capacity then it will…

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(a) Which coloured surface heated up quicker and explain your answer?

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[2]

(b) The water in the can with the dull black surface began at 20°C and rose to 80°C. The mass of water
in the can is 100g. Calculate the energy gained by the…

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(a) Explain why the copper pipes inside the solar panel are painted black.

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(2)

(b) Each day the average European family uses 100 kg of hot water.
To kill bacteria, the water going into the tank at 20 °C must be heated to 60 °C.

Calculate…

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How many months each year will there not be enough solar energy to provide the hot
water used by an average European family?

.................................................. months
(1)



Power and electricity bills

Power is measured in watts (W) and it is the amount of energy transferred in one
second. So a 60W…

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So the bulb would then have used 0.3 kilowatt-hours of electrical energy.
Electricity companies charge you for every kilowatt-hour of electricity you use.



So, for example, if an electricity company changes you 10p per kilowatt-hour of
electricity used then the bulb has cost you:



Generating Electricity

The way electricity is…

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