How do we get E=pv? [ENDORSED]

[Sue Xu 2K]

When deriving the DeBroglie equation we need the equation E=pv. Where do we get this equation?
Also, if p=mv then E=mv^2. What does this have to do with the Kinetic energy Ek=(1/2)mv^2?

[Michael Koger 3K]

This equation comes from the definition of energy. 1 joule (the unit of energy) is defined as 1 N x m, or 1 [(kg x m^2)/s^2]. Momentum times velocity also yields [(kg x m^2)/s^2]. Therefore, the equation E = pv is merely a restatement of the units of energy.

The formula for kinetic energy is not used in the derivation of the de Broglie equation, so don't worry about it.

I hope this helped!

[Diego Zavala 2I]

and since C is the speed of light, we can rewrite the equation as . Since p=mv, E=pv.