Satellite a has twice the mass of satellite b, and moves at the same orbital distance from earth as satellite b. compare the speeds of the two satellites.

given,

mass of satellite A = 2 * mass of satellite B

orbital speed is given by v = SQRT(G*M/R)

where M is the mass of earth

since the velocity is independent of the mass of satellite so,

The speed of B is equal to the speed of A

pythagoras' theorem

square root (-5^2+9^2)

square root (25+81)

square root (106)

angle is tan^-1(9/5)

neg x, pos y

3. dark matter

empty space could also be a simple vacuum