[I] = [MLT⁻³]
Here's how we arrive at this:
* Intensity (I) is defined as the power (P) transmitted per unit area (A).
* Power (P) is the rate of energy transfer, which has the dimensions of energy (E) per unit time (T): [P] = [ET⁻¹]
* Energy (E) has the dimensions of work, which is force (F) times displacement (L): [E] = [FL]
* Force (F) is mass (M) times acceleration (LT⁻²): [F] = [MLT⁻²]
Putting it all together:
[I] = [P/A] = [ET⁻¹/L²] = [MLT⁻² * L * T⁻¹ / L²] = [MLT⁻³]
