Light with an energy flux of `40W//cm^(2)` falls on a non-reflecting surface at normal incidence. If the surface has an area of `20cm^(2)`, find the average force exerted on the surface during a `30min` time span.

Explanation

To solve the problem, we will follow these steps:

### Step 1: Calculate the total energy incident on the surface
The energy flux (intensity) of light is given as \(40 \, \text{W/cm}^2\). We need to convert this to \( \text{W/m}^2\) and then calculate the total energy incident on the surface over a time span of 30 minutes.

1. Convert the energy flux to \( \text{W/m}^2\):
\[
40 \, \text{W/cm}^2 = 40 \times 10^4 \, \text{W/m}^2 = 4 \times 10^5 \, \text{W/m}^2
...