Pressure-Force Cross-Scan - Electromagnetic Radiation Pressure and Momentum Step by Step

Pressure is scanned across irradiance and mode, then force across area. Exact arithmetic here means exact results for the stated model inputs; measured inputs still carry uncertainty and significant-figure limits.

highlighted = computed this step

Pressure divides irradiance by speed

For an absorber, the pressure is the normal irradiance over the training speed. A mirror doubles that momentum change.

p=I/c=6/6=1\ \text{Pa}

Mode and irradiance both change pressure

The rows separate two effects: more irradiance raises pressure, and the mirror mode doubles the absorber value.

\begin{array}{c|c|c|c}\text{mode}&I&c&p\\\text{absorber}&3\ \text{W}/\text{m}^{2}&6\ \text{m}/\text{s}&\frac{1}{2}\ \text{Pa}\\\text{absorber}&6\ \text{W}/\text{m}^{2}&6\ \text{m}/\text{s}&1\ \text{Pa}\\\text{mirror}&6\ \text{W}/\text{m}^{2}&6\ \text{m}/\text{s}&2\ \text{Pa}\\\end{array}

Pressure becomes force only after area is included

Pressure alone is not a force. The illuminated surface area is the second checked input.

\begin{array}{c|c|c}p&A_s&F\\1\ \text{Pa}&2\ \text{m}^{2}&2\ \text{N}\\1\ \text{Pa}&3\ \text{m}^{2}&3\ \text{N}\\1\ \text{Pa}&6\ \text{m}^{2}&6\ \text{N}\\\end{array}