Answer
$p_r = 13.2~Pa$
Work Step by Step
In part (a), we found that the beam intensity is $~~I = 3.97\times 10^9~W/m^2$
We can find the radiation pressure on the sphere:
$p_r = \frac{I}{c}$
$p_r = \frac{3.97\times 10^9~W/m^2}{3.0\times 10^8~m/s}$
$p_r = 13.2~Pa$
