Why do we base energy on work?

[freefall]

Instead of impulse, for example? They are both conserved.

 

When putting energy into an object, its \delta velocity is not directly proportional to the KE added (but is directly prop. to impulse). For this reason we say that a car needs more gas to accelerate by a constant amount the faster its moving (see other thread). But it doesn't take more impulse. If we based energy on impulse, we wouldn't say it takes more gas. Right?

 

Can someone explain?

thanks!

[swansont]

We base it on work because work and energy are directly related. Work is the transfer of energy.

[freefall]

yes, but why is it that, say, gasoline can store a certain amount of energy and not a certain amount of ability to to impulse?

[Bignose]

I suspect you could develop an entire working system of physics based on impulse instead of work. You would have to redefine everything to work in the new system of definitions.

 

Nevertheless, the current definitions we have no seem to work pretty darn well at describing what is seen in nature.

 

And in that respect, even if you redefine the mathematics, nature will take no notice whatsoever. It will take a certain amount of gas to change the velocity a certain amount no matter if you call that quantity impulse, or work, or energy, or ether, or breakfast cereal, or sloths, or footballs. Nature takes no notice of what equations we use to describe nature. And the judgement we use on how good an equation is, is how well does that equation describe nature -- certainly not the other way around like you are trying to do.