11th Physics Volume

and time taken for it is the time period, T. Then Speed v Distance travelled Time taken h Unit Gravitation By substituting these values, the distance to the Moon from the surface of the Earth is calculated to be . × km . . . Energy of an Orbiting Satellite The total energy of a satellite orbiting the Earth at a distance h from the surface of Earth is calculated as follows; The total energy of the satellite is the sum of its kinetic energy and the gravitational potential energy. The potential energy of the satellite is, U GM M h s ( . ) Here M s - mass of the satellite, M E - mass of the Earth, R E - radius of the Earth. The Kinetic energy of the satellite is K E M v s = ( . ) Here v is the orbital speed of the satellite and is equal to GM h