Planet X has mass three times that of Earth and a radius twice that of Earth. a) Show that the acceleration due to gravity on any planet is given by
, where G is the Universal Gravitational Constant and M is the mass of the planet. ​

Two cannon balls weighing 18 kg and 24 kg are chained together and fired horizontally with a velocity of 165 m/s from the top of a 21-m wall. the chain breaks during the flight of the cannonballs and the 18-kg cannonball strikes the ground at t = 1.5 s, at a distance of 240 m from the foot of the wall, and 7 m to the right of the line of fire. determine the position of the other cannonball at that instant. neglect the resistance of the air.