• Join over 1.2 million students every month
• Accelerate your learning by 29%
• Unlimited access from just £6.99 per month
Page
1. 1
1
2. 2
2
3. 3
3

# Energy revision notes

Extracts from this document...

Introduction

Energy revision notes

Sun gives out vast quantities of energy in form of electromagnetic waves, much of it as light energy.

Sound energy also travels as waves, carrying energy away from the vibrations of a noisy object.

Nuclear power stations generate electricity from the nuclear energy possessed by atoms, by splitting large atoms into 2. The sun also releases nuclear energy by joining small atoms together.

A cyclist has energy stored in his muscles. The chemicals in his muscles supply the energy and change when the muscles are used. This form of stored energy is called chemical energy. A motorbike uses energy stored in the petrol. The petrol has chemical energy because its chemicals change when it is burnt.

A skier at the top of the hill has gravitational potential energy. This is energy that is there ready to be used because of the pull of gravity.

Energy is also stored in stretched elastic or springs.

Middle

Total energy input = useful energy output + wasted energy output

The efficiency of a device is the fraction of the energy supplied to the device, which is usefully transferred.

% Efficiency = useful energy transferred by device divided by total energy supplied to device X 100%

The useful energy got out is usually less than the total energy put in, due to friction in most machines, and so efficiency is less than 100%. It cannot be greater than 100%!

Is someone is doing work there is movement against an opposing force.

Energy is transferred to the object that person is moving.

The amount of energy transferred depends on the size of the force and the distance the object moves in the direction of the force.

If the person pushes against a larger force or moves it a greater distance she will do more work.

Work done (J) = force (N) X distance moved (M)

Conclusion

Weight (N) = mass (kg) X gravitational field strength (N/kg)

To lift the object a vertical height, the work which must be done on the object, (energy transferred) is weight X vertical height.

Gravitational potential energy gained (J) = weight (N) X vertical height raised (m)

= Mass (kg) X gravitational field strength (N/kg) X height (m)

When work is done to change the shape of an object, the energy transferred is stored as elastic potential energy.

The greater the force needed to squash a spring or to stretch elastic or a spring, and the greater the movement (compression or extension), the more work is done, and so more energy is transferred.

Kinetic energy is the energy an object has due to its movement. The greater the mass of the object and the greater its speed, the more kinetic energy it has.

Kinetic energy, mass and speed are related by:

Kinetic energy (J) = ½ mass (kg) X (speed)  (m/s)

This student written piece of work is one of many that can be found in our GCSE Electricity and Magnetism section.

## Found what you're looking for?

• Start learning 29% faster today
• 150,000+ documents available
• Just £6.99 a month

Not the one? Search for your essay title...
• Join over 1.2 million students every month
• Accelerate your learning by 29%
• Unlimited access from just £6.99 per month

# Related GCSE Electricity and Magnetism essays

1. ## Converting gravitational potential energy into kinetic energy.

This is why, unlike the other measurements, it gained less than half of the potential energy it stored. Another factor which may have caused this anomalous result could have been that the height of the runway itself wasn't set

2. ## Science + Chemistry revision + Electrostatics

Field lines are imaginary lines that indicate the direction and strengt of an electric field at a point in the field. If field lines are close together it shows a strong field. Field lines never cross, their direcetion is from positive to negative.They always begin and end at right angles to a surface.

1. ## Factors Affecting the Efficiency of a Wind Turbine

In this experiment 30� proved to show a better performance than others. Results didn't confirm my expectations but showed that the greatest angle that will enable us to achieve maximum efficiency is 30� and maybe less. BLADE LENGTH This is a new aspect, which will be investigated, and conclusion drawn on how efficiency can be improved by changing it.

2. ## Trolley Mass and Gravitational Field Strength Investigation

have more potential energy, which means it, would go faster which leads to an increase of friction and air resistance. An increase of air resistance and friction means that more energy is converted to heat energy. I predict that the steeper the slope the faster the trolley will be because the trolley will have more energy.

1. ## Testing the strength of electromagnets

I have also decided to keep the voltage to 4 volts. This is because it is a fairly low voltage and is quite safe, bearing in mind there are bare wires in this experiment. Also I have chosen this low voltage because it means from the findings of my preliminary

2. ## The topic of which I have been studying is energy transfers, how energy can ...

To find the average I will add all my three results up and divide them by three giving me the average. When finding my speed I will use the equation 1�average time this will give me the calculated speed. Diagrams Equipment Ball Ramp Bench When ball rolls down ramp When

1. ## Identifying the science involved in nuclear fusion and is it the energy for the ...

Currently the sources of energy we use are: 1. Fossil fuels: These include coal, oil and gas. The two major problems with the use of fossil fuels is the amount of toxic waste products emitted from combusting these fuels and also the fact that it will eventually run out in the next 90 years to come.

2. ## Molecular stability (rheology) of a plastic carrier bag through stress - strain tests.

Therefore I must keep the experiment at, to a degree, a simplistic level. The large cost of the testing of polymers in the industry justifies the importance of the material to society. This relates with why that safety is needed when testing the material, I shall later resolve safety procedures.

• Over 160,000 pieces
of student written work
• Annotated by
experienced teachers
• Ideas and feedback to