Energy is an abstract concept that is difficult to describe yet we all have some perception of what it is. It can be related to work and forces; "work" transforms energy from on type to another. The resulting "energy" can be seen as the motion of an object on which a force has done some work.

Kinetic energy is proportional to the speed of an object. In fact, it is proportional to the square of the speed (0.5mv^2, where m is the mass and v is the speed of the object).

There is a connection between the temperature of an object and how much heat is in it. Heat is a quantity of energy contained in an object; this "quantity" can be moved from one place to another. Temperature, while varying with the heat content (as a single object's heat content increases, the temperature increases), cannot be moved directly, since it is a description of some characteristic of the individual molecules in an object (the average speed of a molecule).