Why Do Units on Plank's Constant Include Mass, Length, and Time?

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Planck's constant is expressed in units of m² * kg / s due to the underlying relationships between mass, length, and time that were not fully understood when these units were established. It fundamentally represents the relationship between energy and frequency, defined by the equation h = E/ν. This highlights that Planck's constant can also be viewed in terms of energy multiplied by time. Understanding these connections requires familiarity with classical mechanics and how energy relates to mass, length, and time. The discussion emphasizes the importance of these foundational concepts in physics.
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The units on Plank's constant is m^2 * kg / s
I'm new to all of this stuff so... Why?
 
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Because when people devised units, they didn't realize that there are equivalence relationships between length, mass and time.

But to more directly answer your question, Planck's constant really has units of (energy)(time). To see this, note that Planck's constant can be defined by the ratio of the energy and frequency of a photon :

h= \frac{E}{\nu}.

In order to explain the relationship of energy to units of mass, length and time, you might want to consider basic formulae from classical mechanics.
 

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