a man can row a boat at 4 km per hour in still water. he rolls the boat two kilometre upstream and 2 kilometre back to a starting place in 2 hours how fast is the stream flowing

In a system with only a single force acting upon a body, what is the relationship between the change in kinetic energy and the work done by the force? answers: work is equal to the change in kinetic energy.work depends on the square of the change in potential energy.work is equal to the negative of the change in kinetic energy.work is equal to the square of the change in kinetic energy