Thursday, 29 November 2012


1. What do living things need to carry out their life processes and daily activities?
A. Food     B. Water     C. Energy     D. Machines

2. Diagram 1 shows four types of activities.





Which activities require energy to carry out?
A. P and Q only     B. R and S only     C. P, Q and S only   D. P, Q, R, S

3. Diagram 2 shows two objects.


                                                                            Diagram 2

What can we get from the objects in the diagram?
A. Light     B. Heat     C. Energy     D. Electricity

4. What form of energy is stored in firewood and coal?
A. Chemical energy     B. Potential energy     C. Light energy     D. Heat energy

5. Diagram 3 shows a ball at the top of an inclined plane.
What form of energy does the ball have?
A. Potential energy     B. Chemical energy     C. Kinetic energy     D. Heat energy

6. Diagram 4 shows an electric circuit.
What energy transformation takes place when the switch in the circuit is closed?
A. Potential energy---heat energy---light energy
B. Potential energy---electrical energy---light energy
C. Chemical energy---electrical energy---heat energy---light energy
D. Chemical energy---heat energy---electrical energy---light energy

7. Which of the following shows the use of non-renewable energy?
A. Solar energy is used to heat water in homes.
B. Windmills are used to generate electricity.
C. Biomass fuels are burned to release heat.
D. Petroleum is burnt to move vehicles.

8. Diagram 5 shows a hydroelectric power station.

which statements about the energy source are correct?
I     It will not be depleted.
II   It does not produce greenhouse gasses.
III The kinetic energy of water is transformed into electrical energy.
IV Building the dam will flood a large area, causing habitat destruction.

A. I and III only     B. II and III only     C. I. III and IV only     D. I, II, III and IV only

1. C    2. D    3. C    4. C    5. A    6. A    7. D    8. D


1. Coal, petroleum and natural gas are called fossil fuels.  

2. Biomass fuels are obtained from plants and the organic waste of animals.

3. Mechanical energy is the total kinetic energy and potential energy of an object.


3. Nuclear energy is energy stored in the nucleus of an atom. It can be used to create atomic bombs and nuclear weapons.


4. Principle of conservation of energy: Energy cannot be created or destroyed but it can be transformed from one form to another.

5. The use of non-renewable fuels has increased the amount of carbon dioxide and other gasses in the atmosphere, causing the greenhouse effect. This has resulted in global warming and climatic changes.


6. Use firewood instead of coal as fuel because firewood is renewable.

7. Trees which have been cut down for firewood are replaced through replanting.

8. This will conserve the sources of firewood and reduce the use of coal.

Monday, 26 November 2012


1. We need to do whatever we can to conserve energy sources so that are not depleted too quickly.

What we should do?????

  • Use renewable energy sources as alternatives.
  • Switch off lights and electrical appliances when not in use.
  • Use recycled materials.
  • Use energy-efficient lamps such as fluorescent lamps.
  • Use public transport such as buses and trains. Car pool to reduce congestion and petrol consumption.
  • Develop biomass fuels for transport.


1. Non-renewable energy sources take millions of years to form.
2. They cannot be replenished within a short time once they are used up.
3. There will be on energy crisis once these energy sources run out.
4. We need to use these sources wisely to

  • save cost
  • prevent wastage
  • reduce pollution
  • ensure there is enough energy for the future

Sunday, 25 November 2012


1. The energy we use every day comes from two major sources: renewable energy and non-renewable energy sources.
2. Renewable energy is energy that can be replenished. Such energy sources are always available.
3. Non-renewable energy is energy that cannot be replenished when it is used up.

Renewable Energy Sources

The Sun 

  • Solar energy comes directly from the Sun.
  • Solar energy is used to heat water in homes and to produce electrical energy.


  • Wind is moving air. It has kinetic energy.
  • Windmills transform this energy into electrical energy.

  • Energy in water is used to generate electricity in hydroelectric power stations.
  • Biomass energy is obtained from plant and animal waste materials.
  • The burning of biomass fuels releases heat energy and generates electrical energy.
Non-Renewable Energy Sources

                                                                          Natural gas                      
Nuclear reactor
  •  Fossil fuels such as coal, petroleum and natural gas are burnt to produce heat energy for cooking and    moving vehicles and machines.
  • These fuels can also be used to generate electricity.
  • Nuclear energy is produced in nuclear reactors.
  • Nuclear energy is used to generate electrical energy and power submarines, ships and satellites.

4. Renewable energy sources are better than non-renewable energy sources because
  • they cannot be used up
  • there is little or no pollution


1. Many invented appliances are based on the principle of energy transformation.
2. Energy transformation enables us to carry out various activities in everyday life.
3. The following are some appliances that make use of energy transformation.

 Electrical energy
light energy + sound energy

Electrical energy
heat energy + sound energy

Washing machine
Electrical energy
sound energy

Table fan
Electrical energy
kinetic energy
sound energy

Electric iron
Electrical energy
heat energy

Gas stove
Chemical energy
light energy + heat energy

Electric drill
Electrical energy
kinetic energy + sound energy


1. Energy can be transformed from one form to another.
2. Energy transformation is used in our daily activities.

Switching on lights

When a table lamp is switched on, electrical energy is supplied to the lamp. The bulb in the lamp changes the electrical energy into light energy and heat energy.

                                                         Electrical energy

light energy + heat energy
A lit matchstick

A lit matchstick contains chemical energy. When a matchstick is lit, chemical energy is transformed into light energy and heat energy.

Chemical energy
light energy + heat energy

Using a solar-powered calculator
The solar cells on a calculator absorb solar energy and transform it into electrical energy. The electrical energy is then changed into light energy.

Solar energy
electrical energy
light energy

Winding up a toy car and releasing it

When the spring of the toy car is wound, kinetic energy is changed into potential energy stored in the spring. When the toy car is released, the potential energy is transformed into kinetic energy and sound energy.

Potential energy
kinetic energy + sound energy


1. energy can be found in various forms.

Chemical energy

  • Stored in food, fuels and batteries.

                                            batteries                                                                              food
Heat and Light energy
  • Released by hot objects such as stoves and bonfires.
  • In objects that give out light, including the Sun, lighted bulbs and candles.
  • Enables us to see.
  • A burning candle


Potential energy
  • Stored in an object in its position or condition.



 Sound energy

  • Produced through vibrations.

                                                                             playing piano

                                                      A ringing telephone

Solar energy
  • Released bu the Sun.

Kinetic energy 

  • In moving objects.

Electrical energy
  • Carried in electric currents.