A 0.54 kg air hockey puck is initially at rest. What will it's kinetic energy energy be after a net force of 0.56 N acts on it for a distance of 0.84m?

Kf = 470 mJ

Explanation:

According the work-energy theorem, the change in the kinetic energy of one object, is equal to the net work done on it.Since the puck is initially at rest, the change is kinetic energy is just the final kinetic energy of the puck.Assuming that the net force is horizontal, and causes a horizontal displacement also, we can find the net work on the puck as follows:

       

As we have already said, (1) is equal to the final kinetic energy of the puck:⇒ Kf = 470 mJ  (2)

Iwould think it would be 2.6