Random equation curiosity

[sfpublic]

hi, I am using the equation E=h^2/pv

 

E=Energy

h=Planck const

p=momentum

v=velocity

 

How might I test to see if this is correct?

[swansont]

hi, I am using the equation E=h^2/pv

 

E=Energy

h=Planck const

p=momentum

v=velocity

 

How might I test to see if this is correct?

 

Check the units. It won't tell you an equation is right, but can tell you when it's wrong.

 

pv has units of energy. h has units of energy*time. [math]\frac{h^2}{pv}[/math] does not have units of energy.

[Mr Skeptic]

Check the units. It won't tell you an equation is right, but can tell you when it's wrong.

 

pv has units of energy. h has units of energy*time. [math]\frac{h^2}{pv}[/math] does not have units of energy.

 

Very true. Units are a simple, easy to use sanity check. Now if you correct the units, [math]E = \frac{h^2f^2}{pv}[/math], where f is frequency, you get an equation that gives the energy of a photon (but not for anything else). Of course, that is a coincidence and you cannot count on it. In this case, it is because of two different equations for a photon's energy, [math]E_{photon} =hf[/math] and [math]E_{photon} = pc[/math].

 

So as swansont said, make sure the units match.