What was the speed of a space shuttle that orbited earth at an altitude of 1482 km?

What is the relationship between the wavelength of a wave and it's energy?

Which accurately compares concave and convex lenses?

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?