# physics dealing with orbital speed help pls asap?

on a typical mission the space shuttle (m=2.00*10^kg) orbits at an altitde of 700 km above the earths surface. dose the orbital speed of the shuttle depend on its mass?

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No! The orbital speed is found by the formula:

V orbital = sqrt (GMp) / r

G is gravitational constant

Mp is the mass of the central object, in this case the earth

r is the orbital radius ( center of the earth to the center of the orbiting object)

So a baseball would orbit the earth at the same speed of the space shuttle if both are at the same altitude above the earth.

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• This is a trick question: Conservation of angular momentum would tend to suggest that the velocity should increase, since the distance from the center of revolution is decreasing... HOWEVER: angular momentum is not conserved, since there is a force acting on the satellite. What is actually happening is that for any orbit (or any circular motion, for that matter) the centripetal force must be m*v^2/r (m = mass, v = velocity, r = distance to center of revolution, or 1/curvature, if you prefer). In the case of circular motion, that force is supplied solely by gravity. Since this is happening over a large distance, we use Newton's formula for gravity, instead of the simplified one. Thus: F = G*m1*m2/r^2 = m2*v^2/r We cancel the two m2s, and one of the rs, and neglect the effect of G and m1, since they are both constants in this problem, thus: c/r = v^2 where c is a constant, or v^2 r = c Thus, if r decreases, v^2 (and, in turn, v) must increase

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