GRADE LEVEL/SUBJECT: 3-8, science

PURPOSE: The purpose of the following experiment is to
demonstrate that energy from the sun can be collected and
stored in many ways.

RESOURCES/MATERIALS: one plastic bottle painted white, one
plastic bottle painted black, several small balloons

ACTIVITIES AND PROCEDURES: General information -
Our sun is an average sized star and it has been burning
for about 4.5 billion years. Few people think of the sun as
a nuclear furnace and fewer realize this is a source of
nuclear energy that does not pollute. About four million
tons of the sun's matter turns into energy every second and
only one-billionth of the sun's light ever strikes the
Earth.

At the equator the Earth receives about one kilowatt per
square meter of solar energy. A kilowatt is 1000 watts of
or the amount of energy needed to light 10 one-hundred watt
bulbs. If man could make full use of solar energy, almost
every house in the world could be energy independent. Only
a few households would have to be dependent on the electric
company and this would reduce the pollution problem greatly.
The consumption of gas, oil, or coal would be reduced and
this would also help reduce the level of pollution. The
automobile could be powered by the sunlight during the day
and use battery power at night. This would also reduce
pollution and help prevent global warming.
Turning solar energy directly into electricity today is
not very efficient; however, solar energy can be best
collected as heat. The following experiment will teach
young people how to collect and store the sun's energy in
the form fo heat.

The teacher will notice the experiment demonstrates a
method to collect and store solar energy and has been
designed for grade one through six. It is possible for
young students to expand the concepts of these experiments
into local science fair projects.

The Black and White Bottle Experiment
The experiment is performed with the two plastic bottles.
The teacher will note one bottle is painted black and the
other is painted white. Place the open end of one small
balloon on the mouth of the white bottle and do the same for
the black bottle. Make sure the balloon forms an air tight
seal. Now place both bottles in bright sunlight. Within a
few minutes, the students will notice the balloon on t he
black bottle will start to expand. The balloon of the white
bottle will remain limp. Have a student touch the black
bottle to notice that it is warm. Then have the same
student touch the white bottle to notice that it is much
cooler than the black bottle.

Questions -
1. Why do you think the balloon on the black bottle
expanded?
2. Does heat make air expand?
3. Does a black object get warmer in the sunlight than a
white object?
4. What would be a good color to paint your car if you
wanted to stay cool in the summer?

Explanation -
The black bottle will absorb the sun's energy much better.
The white bottle reflects away most of the sun's energy. As
the bottle absorbs energy, the air inside the bottle warms
up and expands making the balloon full with air.