An apple is a favorite example to illustrate a one joule of work when using the definition given earlier (i.e., the amount of work done…) because an apple weighs approximately one Newton. Thus, you’d have to exert a one Newton upward force to counteract its one Newton weight. Once you’ve lifted it up to a height of one meter, you would have performed one joule of work on it.
Now, how does energy fit into the picture? As you perform work on the apple, the energy of the apple (in this case, its potential energy) changes. At the top, the apple would have gained about one joule of potential energy.
Also, when the apple is one meter above its original position, say the floor, gravity would have gained the ability to do work on it. This ability, when measured in joules, is equivalent to one joule.
Meaning, when you release the apple, the force of gravity, which is simply just the weight of the body and equivalent to one Newton, would be able to perform one joule of work on it when the apple drops down from a height of one meter.