Q. When a single person shouts at a football game, the sound intensity level at the center of the field is 57 dB. When all the people shout together, the intensity level increases to 107 dB. Assume that each person is about the same distance from the center of the field and can generate the same level of sound intensity. How many people are at the game?
Q. Three equal point charges, each with charge 1.60 mu C, are placed at the vertices of an equilateral triangle whose sides are of length 0.450 m. What is the electric potential energy U of the system? (Take as zero the potential energy of the three charges when they are infinitely far apart.)