Question

The radius of the earth s 6.38 x 106m. If a satellite is in orbit around the earth at an altitude of 1500km, what is the speed of the satellite? 

Answer 1

$$v=\sqrt{\dfrac{GM}{R+h}},$$ $$v=\sqrt{\dfrac{6.67\cdot10^{-11}\ \dfrac{Nm^2}{kg^2}\cdot5.98\cdot10^{24}\ kg}{6.38\cdot10^6\ m+1.5\cdot10^6\ m}}=7.11\ \dfrac{km}{s}.$$