under the influence of its drive force, snowmobile is moving at constant velocity along a horizontal patch of snow. When drive force is shut off, snowmobile coasts to a halt.

a) During the coasting phase, what is the net external force acting on the snowmobile
b) How does work W done by the net external force depend on the magnitude anddirection of the net force and on displacement of the snowmobile?
c) What is the net force acting on snowmobile during constant-velocity phase?