What are the units for the equation E=gamma*m?

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The equation E=gamma*m involves energy (E) measured in Joules and mass (m) in kilograms, while the Lorentz factor (gamma) is dimensionless. For calculations involving the Lorentz factor, it is essential that energy and mass are in compatible units. The length contraction equation L=L0*gamma requires that length (L) is measured in meters, with L0 representing the proper length in the rest frame. The discussion also mentions the use of natural units, suggesting that mass and energy can be expressed in Planck units for consistency. Understanding these units is crucial for accurate calculations in relativistic physics.
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I'm using the equation: E=gamma*m

I want to know what the units of each of the quantities are. If I want to calculate the Lorentz factor, then do I need to make sure that both the Energy and mass have the same units?

I am also using the equation for length contraction: L=L0*gamma

Do I need to make sure that the length is in metres? And is L0 the length in the rest frame?
 
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The formula relating E and m is E = mc². m in kg, E in Joules.
The gamma factor 1/sqrt(1-v²/c²) is dimensionless (no units).
It relates two times or lengths (moving to stationary measurements) as in length contraction and time dilation.
 
Oh, thank you! I haven't seen natural units for many years.
The article you linked answers your question: you must put the mass and energy in Planck units. The SI equivalents for the Planck units for mass and energy are listed in tables here:
http://en.wikipedia.org/wiki/Planck_units
 

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