Radiation
from the Sun striking the Earth has an intensity of
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Solution: Click For PDF Version We will use the following astronomical data in answering this problem:
Mass of the
Sun,
Mass of the
Earth,
Mean orbital
radius of the Earth,
and
Mean radius
of the Earth,
Force on the Earth due to the radiation pressure will be equal to the momentum transferred per unit time to the Earth because of the absorption of the solar radiation. Therefore, the force on the Earth due to the absorption of the solar radiation assuming that the Earth behaves like a flat disk at right angles to the Sun’s rays will be
And by the Newton’s law of universal gravitation, the gravitational force on the Earth due to the Sun will be
Therefore,
|
.
(a) Assuming that the Earth behaves like a
flat disk at right angles to the Sun’s rays and that all the
incident energy is absorbed, we
have to calculate the force on the Earth due to the radiation
pressure; we will
compare it with the force due to sun’s gravitational attraction
by calculating
.
’
,
,
.
