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Let us assume the satellites move in a circular orbit around the Earth, whose ra

ID: 1691173 • Letter: L

Question

Let us assume the satellites move in a circular orbit around the Earth, whose radius is RE=6378 km. To stay in orbit the centripetal force must balance the gravitational force, i.e.,

                                  mv2/R = GmEm/R2


where v is the tangential velocity, m is the satellite mass, G is the gravitational constant (G=6.673x10-11 Nm-2 kg-2), mE is the mass of Earth, and R is the orbit radius.

a) If the period of the orbit is defined as express the period in terms of R, G, and mE.

b) A geostationary satellite moves in a counterclockwise sense at exactly the same speed as the Earth at a chosen altitude above the equator. Find the altitude of the satellite.

(Hint: Angular velocity of Earth is 7.29221x10-5 s-1 and angular velocity of the satellite is given by )
Let us assume the satellites move in a circular orbit around the Earth, whose radius is RE=6378 km. To stay in orbit the centripetal force must balance the gravitational force, i.e.,

                                  mv2/R = GmEm/R2


where v is the tangential velocity, m is the satellite mass, G is the gravitational constant (G=6.673x10-11 Nm-2 kg-2), mE is the mass of Earth, and R is the orbit radius.

a) If the period of the orbit is defined as express the period in terms of R, G, and mE.

b) A geostationary satellite moves in a counterclockwise sense at exactly the same speed as the Earth at a chosen altitude above the equator. Find the altitude of the satellite.

(Hint: Angular velocity of Earth is 7.29221x10-5 s-1 and angular velocity of the satellite is given by )

Explanation / Answer

(a) mv^2 / R = Gmm_E /R^2 v^2 = Gm_E / R velocity   = sqrt(Gm_E / R) time period  T = 2*pi*R / v = 2*pi*R /sqrt(Gm_E / R) Here R is radius of the earth m_E mass of the earth ------------------------------ (b) g = Gm_E / R^2 here R = R_E + h h is height from the surface of the earth R_E + h = sqrt (Gm_E /g ) alltitude h = sqrt (Gm_E /g ) - R_E