2007-03-29 19:28:38 · 5 answers · asked by maths maestro 1 in Science & Mathematics ➔ Physics
An interesting question! If we assume that a body with mass has momentum, mv, then it also has kinetic energy, 1/2 mv^2.
Of course the velocity vector is always relative to the observer when measuring this momentum and energy. So, if you are speeding along next to the body, it has no momentum that you can observe. And no kinetic energy either, relative to you. However, you make a last minute course correction as the body splats into a brick wall, so as to safely observe the change in momentum and kinetic energy.
On the other hand, a body can have something other than kinetic energy. It could be hotter than the surrounding environment and emit radiant energy. Or maybe its just noisy and emits acoustic energy. All without gaining or losing any momentum, mostly. I say mostly because even photons, which are electromagnetic energy, have momentum, even though they have no mass to carry that momentum. Go figure.
So, depending on how you look at it, you can have energy without any appreciable momentum, but I don't see how you could have momentum without also having kinetic energy associated with that momentum.
2007-03-29 20:26:53 · answer #1 · answered by hevans1944 5 · 0⤊ 0⤋
Actually, the theory of relativity has equated energy and momentum and being two forms of the same thing. According to relativity, a body at rest has both momentum and energy, defined by relativistic formulas. Another issue is that energy appears in many forms (heat, potential, etc.) But relativity says that even these forms of energy have momentum (mass).
2007-03-29 19:41:38 · answer #2 · answered by gp4rts 7 · 2⤊ 0⤋
it is not possible for a body to has no energy, but some momentum, but it is possible for a body to has no momentum but some energy. E.g. Potential energy
2007-03-29 19:33:29 · answer #3 · answered by huzaifahar2000 2 · 0⤊ 0⤋
It is physically impossible for a body to have "no" energy. Everything from the atom to the cell are created out of energy. The core of your entire being is energy based. Even a dead body has energy in it.
2007-03-29 19:33:27 · answer #4 · answered by Chillyboy 3 · 1⤊ 0⤋
yes. an object floating in space has no energy but has momentum. A battery has no momentum but has energy.
2007-03-29 19:32:38 · answer #5 · answered by Anonymous · 1⤊ 1⤋