Energy that is stored is called potential energy. Take a round ball that is at rest at the top of the hill. The ball has a lot of potential energy, but no kinetic energy because it is not moving. Once the ball is released and it begins to roll, the potential energy the ball had initially is transformed into kinetic energy. The higher the ball is placed, the potential energy it will have. A-more B-less

answer : a model is often used to explain and make things easier to understand when any scientific topic needs to be demonstrated and explained.

as in this case where a scientist wants to use a model to present the results of his detailed scientific investigation. he should do it as it will him to make the audience understand the concept in a much better way. also, it can be changed according to new scientific understandings.