Think of a bicyclist as a machine for a moment. All machines have an input and an output. For instance, a sewing machine uses electricity to make the needle go up and down. An automobile coverts the energy stored in gasoline into mechanical energy to make the car go forward.

A bicyclist is not much different in principle – the cyclist eats food which, in turn, makes muscles move. The food the cyclist eats contains energy stored as chemical potential energy. All foods contain an assortment of large and small molecules which the body breaks down during digestion to make its fuel. This fuel is delivered along with oxygen (that we inhale) to every cell in our body.

Even when a person is sleeping energy is still being used by the body. Our heart pumps blood througout the body, our diaphragm allows us to breathe, and our brain is active 24 hours a day. In order to meet this minimum energy requirement a particular amount of food must be consumed.

Just as a car that drives very fast requires more gasoline than a car that drives very slow, bicyclist riding for 7 hours per day has higher energy requirements than a sedentary person. To meet this increased energy requirement, I will have to eat more food than I typically do.

The law of conservation of energy is a fundamental law by which all things in the world are governed. It states that energy cannot be created nor destroyed, but it can be converted into different forms of energy. A cyclist converts the food energy he eats into mechanical energy that propels the bicycle forward.

-more to come soon.