# What are the units for m in the average kinetic energy formula?

For the equation $E_k=\frac{1}{2}mu^2$ what does the $m$ variable represent?

I would say mass but the textbook does not say explicitly that it is anything.

$$\ce{Kinetic ~Energy ~= ~1/2 (mass~of ~the~object~ [kg]) * (velocity~of~the~object~[m/sec])^2}$$

• I'm not sure if the $u$ should be $\bar{u}$ and so the $m$ should be the mass of one molecule. – jonsca Jul 9 '14 at 17:38
• (if you were keeping that under your hat for the time being, I apologize :) ) – jonsca Jul 9 '14 at 17:41
• I cannot overcome a temptation to post this old anecdote: A physicist was hospitalized after a car accident. He lies and groans: - Ahh it's so good it's half. So nice it's half... - What's about this "half" thing? - the doctor asks. - It's amazing that the kinetic energy is only half em vee squared! - says the poor guy with a smile:) – andselisk Oct 15 '17 at 10:22

$$E_k = \frac{1}{2}mu^2$$

where, $m$ is molar mass (unit - kg/mol), and $u$ is root mean square speed.

According to wikipedia,

The molar mass of atoms of an element is given by the atomic mass of the element multiplied by the molar mass constant.

$$E_k = \frac{1}{2}mv^2$$ $E_k$ is the average kinetic energy, m is the molecular mass and $v^2$ is the average of the squares of the molecular speeds. (if you're dealing with one particle, its just the velocity of said particle)