Question
53. An artificial Earth satellite is moved from a circularorbit with radius R to a circular orbit with radius 2R. During this move: A) the gravitational force does positive work, the kineticenergy of the satellite decreases, and the potential energy of the Earth-satellite systemincreases B) the gravitational force does positive work, the kineticenergy of the satellite increases, and the potential energy of the Earth-satellite systemincreases C) the gravitational force does negative work, the kineticenergy of the satellite system increases, and the potential energy of the Earth-satellitesystem decreases D) the gravitational force does negative work, the kineticenergy of the satellite decreases, and the potential energy of the Earth-satellite systemincreases E) the gravitational force does positive work, the kineticenergy of the satellite increases, and the potential energy of the Earth-satellite systemdecreases 53. An artificial Earth satellite is moved from a circularorbit with radius R to a circular orbit with radius 2R. During this move: A) the gravitational force does positive work, the kineticenergy of the satellite decreases, and the potential energy of the Earth-satellite systemincreases B) the gravitational force does positive work, the kineticenergy of the satellite increases, and the potential energy of the Earth-satellite systemincreases C) the gravitational force does negative work, the kineticenergy of the satellite system increases, and the potential energy of the Earth-satellitesystem decreases D) the gravitational force does negative work, the kineticenergy of the satellite decreases, and the potential energy of the Earth-satellite systemincreases E) the gravitational force does positive work, the kineticenergy of the satellite increases, and the potential energy of the Earth-satellite systemdecreases
Explanation / Answer
The satellite rises to a higher orbit. So gravity ispulling in the direction opposite the motion, so its work isnegative. Gravitational potential energy is -GMm/r, so thelarger r is, the larger the potential energy. Kinetic energyis (1/2) mv2, and the satellite in its new orbit will beorbiting more slowly, so the kinetic energy decreases. So the answer is D.