A 4kg soccer ball sits on the ground. A boy comes up and kicks the ball 24m. If the work done was 78j, what was the balls velocity.

What is the thinnest soap film (excluding the case of zero thickness) that appears black when illuminated with light with a wavelength of 480 ? the index of refraction of the film is 1.34, and there is air on both sides of the film. express your answer in nanometers. hint 1. how to approach th