Question

If a satellite of mass 400kg revolves around the earth in an orbit with speed 200m/s then it's potential energy is

Answer 1

HEY DEAR ...

PE= -2KE
     = -2x1/2xm*v^2
given ,
mass is 400kg, v=200m/s
on substituting we get PE=-400x200x200
​                                          =-16x10^6 J=-16 megajoules=-16MJ

HOPE , IT HELPS ...

Answer 2

If a satellite move in a circular path,

Centripetal force needed to move it = Gravitational force on a satellite

                                     $mV^{2} /r = GMm/r^{2}$

                                           $V^{2} = GM/r$------ (1)

Where, m = mass of the satellite

            V = velocity of the satellite

            r = radius of the orbit

            G = gravitational constant

           M = mass of earth

Now we can write,

Potential energy of satellite = P.E = - GMm/r

Kinetic energy of satellite = K.E = (1/2)mV²

                                          $K.E = (1/2)m* (GM/r)$        (by (1))

                                          $K.E = (-1/2)* (-GMm/r)$

                                          $K.E = -P.E/2$

                                          $P.E = -2K.E$

                                          $P.E = - (1/2)*400* 200^{2}$

                                          $P.E = 16 *10^{6} J$

                                          $P.E = 16 MJ$