An unmanned research drone of mass 20kg operates on Planet Z, where the surface gravitational field strength is measured to be 15N/kg. Neglect any atmospheric effects unless otherwise specified.
(a) Calculate the magnitude of the gravitational force acting on the drone while it rests on the launch pad at the planet’s surface.
(b) The drone ascends vertically at constant upward speed using its engines. Ignoring air resistance, determine the magnitude and direction of the net force on the drone during this constant-speed ascent. Explain your reasoning.
(c) After reaching an altitude of 2.0km, the engines suddenly fail. At that instant the drone is momentarily at rest relative to Planet Z. Assuming the gravitational field strength remains 15N/kg over this altitude range and neglecting air resistance, determine the speed of the drone just before it returns to the planet’s surface.