A3.65 kg cannon, shot from a 2-meter cannon, accelerates from 0 m/s to 21.34 m/s in 13.59 s. how much force is needed to shoot the cannon ball

The illuminance of a surface varies inversely with the square of its distance from the light source. if the illuminance of a surface is 120 lumens per square meter when its distance from a certain light source is 6 meters, by how many meters should the distance of the surface from the source be increased to reduce its illuminance to 30 lumens per square meter?