Question

Einstein's famous equation indicates that E=mc^2, where c is the speed of light and m is the object's mass. Given this, what is the SI unit for E?

Answer 1

Answer: Joules

Explanation:

Einstein's equation is:

$E=mc^{2}$

Where:

$E$ is the energy

$m$ is the mass and its SI unit is kilogram $kg$

$c$ is the speed of light and its SI unit is meters per second $\frac{m}{s}$

If we input the units in the equation and make the analysis of the units:

$E=kg{(\frac{m}{s})}^{2}=kg \frac{m^{2}}{s^{2}}$

Rearranging the units:

$E=kg \frac{m}{s^{2}}m$

As we know 1 Newton is $1 N=kg \frac{m}{s^{2}}$

$E=Nm$

And 1 Joule is $1J=Nm$

$E=J$ This is correct because the Joule is the SI unit for energy