Aperson's height and weight will change gradually, while other things, such as getting a driver's license, may occur suddenly and mark the beginning of a new phase in life. this difference is an example of the theme of development known as:

Continuity vs. Stages

Explanation:

Continuity is the gradual changes that a person may experiment throught their life, good examples are the ones given in the question, height and weght increasing or changing over time, but stages start whenever something happens that changes the way of life of the person, for example graduating college and going into the labor force, or getting married.

pe = weightxheight = 2000x1000=2,000,000joules