Dirk Van de moortel wrote:

If you don't understand the definition of energy, surely
you can't possibly understand conservation of energy.

Dirk,

Can you provide a definition of energy? When I have
replied to the question "What is energy?" asked by others,
I have said that energy is something one learns about
through experience. Since energy is part of everything
that happens, people naturally acquire a great deal of
experience with it.

But still we need to define the term in some way so that
we know we're talking about the same thing when we use the
term. The standard description of energy that I quote when
I answer the question is that "Energy is the ability to do
work". (I'll go on to describe what work is, if need be.)
But that description seems to fall short of a definition.
Granted, all definitions one can find in a dictionary are
ultimately circular, because in reality all understanding
is based on experience. But is it possible to do better?
Can you define "energy"?

-- Jeff, in Minneapolis