urgent electromagnetism help 1. The problem statement, all variables and given/known data Assume that dust particle in the solar system are spherical, black and have a density of 2000kg/m^3. Use the total luminosity of the sun to calculate the time average poynting vector of the radiation at a distance r from the Sun. Hence estimate what is the maximum size of a dust particle that can be help in orbit by gravity around the sun without being blown away by radiation pressure. 2. Relevant equations 3. The attempt at a solution I have no idea about finding the poynting vector For the second bit do i use P=F/A and F=GMm/R^2, and P(radiation)=S/c?