Re: QUESTION ON LAWS OF MOTION AND NEWTON LAW


<mchristo@xxxxxxxxxxx> wrote in message
news:0b663da9-08af-431c-8d58-3411be2770e1@xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx
well,
suppose we have a planet and that a body is on height H above the
planet. The atmosphere of the planet ends H/2 above its surface. if
the body begins to fall, describe its motion, until it falls on the
surface of the planet.
What I thought in the first place was:

when the body is in vacuum, then the planet exerts a force on it, so
it moves with a constant acceleration, according to Newton's second
law.
But Im not sure about that...Can anyone help me organise my thoughts a
little?

Thank you.

Depends how accurate you want the answer?

The acceleration will depend on the distance from the center of the earth.
However the earths atmosphere is thin. H in relation to the radius of the
earth is small. Therefore acceleration is approx constant over delta H.

If the body is stationary there is no atmospheric drag so the acceleration
is same as it would be just above the atmosphere.







.

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