Amos runs up a flight of stairs with a total change in energy AEA. Vanessa exerts double the amount of energy in twice the time.
How does Amos's power output, PA compare with Vanessa's power output, Pv?

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?