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m 1 v  m 2 v 20
10
v  . (5.44)
m  m 2
1
5.8 Alternative Energy

Energy is the ability to do work. While energy surrounds us in all
aspects of life, the ability to harness it and use it for constructive ends
as economically as possible is the challenge before mankind.
Alternative energy refers to energy sources, which are not based on the

burning of fossil fuels or the splitting of atoms. The renewed interest in
this field of study comes from the undesirable effects of pollution (as
witnessed today) both from burning fossil fuels and from nuclear waste

byproducts. Fortunately there
are many means of harnessing
energy which have less

damaging impacts on our
environment. Here are some
possible alternatives:

Solar energy is one the
most resourceful sources of
energy for the future. One of
the reasons for this is that the

Figure 5.12 total energy we receive each
year from the sun is around
35,000 times the total energy used by man. However, about 1/3 of this

energy is either absorbed by the outer atmosphere or reflected back into
space (a process called albedo)
Solar energy is presently being used on a smaller scale in furnaces
for homes and to heat up swimming pools. On a larger scale use, solar

energy could be used to run cars, power plants, and space ships (like the
picture you see above) . Nellis Solar Power Plant in the United States
(fig.5.12) one of the largest photovoltaic power plants in North

America.
Wind power is another alternative energy source that could be
used without producing by-products that are harmful to nature. Like

solar power, harnessing the wind is highly dependent upon weather and
location. The average wind velocity of Earth is around 9 m/sec. And the
power that could be produced when a wind mill is facing the wind of 10

mi/hr. is around 50 watts.

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