My school textbook states if a ball falls due to free fall, its weight will do work, which is transferred to Kinetic Energy when dropped from a certain height.
Hence, work done = energy transferred.
But then it says this is as 'energy is defined as the capacity to do work'.
What does the term 'capacity to do work' mean?
I am very confused! How does this relate to the subject of
work done = force x distance moved in direction of the force?
Also, it says that if a 40N force is applied on a box that is moving on a rough surface at constant speed, the work done on the box is "transferred into thermal energy between the box and surface below" - but isn't some of the work done transferred into kinetic energy to keep the box moving?