The term ‘energy’ is used in everyday life to mean vigour, forcefulness and activeness. To the sportsman or athlete it means the ability to go on for that longer period which wins the match or race. In science the word ‘energy’ has a similar but very precise meaning.
It means the ability or capacity for doing work. Some mention has already been made of energy in the earlier chap-
ters, and both potential and kinetic energy have been referred to. The purpose of this chapter is to show not only how it may be recognised, but how it may be measured.