Workshop Programme Teachers' Notes
Energy in Motion
Going with the flow: Water power
Waterwheels were used to irrigate crops as long ago as 600 B.C. By the
beginning of the 20th century, waterpower was used to drive machinery to
make paper and spin cotton.
Waterwheels are now called turbines and are used in hydroelectric power
stations. Water is stored behind a dam. As it is released, water drives
turbines and generates electricity. Worldwide, waterpower is the major
source of energy after fossil fuels.
Catching a few rays: Solar energy
All green plants absorb energy from the sun using chlorophyll in their leaves.
Plants trap light energy in special cells and transform the light energy into
chemical energy. This process is called photosynthesis.
Solar panels also collect energy from the sun. One type of solar panel contains
a liquid that absorbs the heat energy. Hot liquid passes to a heat exchanger to
heat the water in a swimming pool or a home's water heater.
The second type of solar panel converts the sun's rays into electricity. The
voltage and power is low, so several cells are connected to each panel.
Collecting and storing energy
Energy that is naturally available needs to be collected to be useful.
Sometimes the energy can be used at the place where it is collected, and
sometimes it must be stored and transferred.
Energy is never created or destroyed, but it may be transferred from place
to place. Energy may change forms, just as LEGO
®
bricks may be put
together in different ways.
Transfer of energy
When energy is transferred from where it is stored to where it is used,
some energy escapes as heat. In an efficient system, most of the energy
collected is available to do work.
Power
Power is a measure of how fast you transfer energy. You can lift an object slowly and work at a low
power. Lift it very quickly and you work at a higher power.
Potential and kinetic energy
Energy changes form in order to be useful:
Kinetic energy is energy of motion. Faster motion increases the kinetic energy.
Potential energy is energy stored in a system at rest. When the position is changed, energy is released.
...Energy cont.
