What is Energy?

What is Energy?

Section C. Measuring and Quantifying Energy

When people say the words energy, work, or power in everyday conversations, listeners usually have little trouble understanding what these words mean. For example, one teacher might say to another, "I put a lot of work into my lesson plan last night and it paid off. Today's class went really well." The other teacher would understand immediately what the first is talking about.

But what are the scientific definitions of energy, work, and power? Energy is often defined as the ability to do work. In turn, work has a specific definition in physics, it is equal to the force needed to move an object multiplied by the distance it moved (Work =  Force x Distance). Although the teacher planning the next day's lesson during the evening may say that he is doing work, by definition, work is done only when the teacher actually moves something, such as moving his pen to write his lesson plan (Taken from the KEEP Activity Guide " People Power"). 

ENERGY

Just as there are many forms of energy, there are different ways to measure these forms. In science, work and energy are commonly measured in joules. One joule is the amount of energy it takes to lift an object that weighs one Newton a one meter distance. A Newton is the metric unit for weight and is comparable to the weight of a stick of butter. (1 Newton = 0.445 lbs.)

In our everyday lives, other energy measurements are more familiar to us than joules. Some of these measurements include calories, therms, andkilowatt-hours. Definitions of these and other units are found below.

It might seem confusing to have so many different measurements for energy. The good news is that one unit can be converted to another.

See Conversion and Resource Tables.