Physics Help Forum Uniform circular motion problem

 Nov 1st 2013, 03:14 PM #1 Junior Member   Join Date: Aug 2011 Posts: 5 Uniform circular motion problem While I was reading a topic I found that when a satellite orbiting the earth at a small radius it moves in a high speed more than a large radius I tried to Know why ?? F = m.a m.g = m.radial accerelation cancel mass g=v^2/r so square velocity is directly proportional to radius which means if the satellite is orbiting with large radius it will have more speed than small radius ???? __________________ ]Nothing is impossible
Nov 2nd 2013, 06:13 AM   #2
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 Originally Posted by mido22 While I was reading a topic I found that when a satellite orbiting the earth at a small radius it moves in a high speed more than a large radius
yes
 I tried to Know why ??
an inquisitive mind will take you far.....
 F = m.a m.g = m.radial accerelation cancel mass g=v^2/r so square velocity is directly proportional to radius which means if the satellite is orbiting with large radius it will have more speed than small radius ????
But g is not constant with height. As the distance from Earth increases, the value of g decreases. You need to look at the universal constant G, where g = GM/(R)^2) , thus , v^2 = GM/R (M is the mass of the earth). As R increases , v decreases. An astronaut in orbit 200 miles up travels at some 18,000 mph, orbiting earth full circle in 90 minutes; A Geostationary satellite in orbit at 25,000 miles up travels at a much slower speed, orbiting earth once in 24 hours ( or about 3,000 mph, rough numbers).

 Jan 10th 2014, 12:39 AM #3 Junior Member   Join Date: Jan 2014 Posts: 1 Say that we orient the plane OAB such that we are looking into the page. ("Vertical" becomes "in the plane of the page.") There's a symmetry here: the plane OAB looks basically the same if we look at it from above the page or below it. So OAB has to be in the plane of the page since there is as much reason for it to be pointed out of the page or into it.

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