Q. A 72kg person sits on a 3.6kg chair. Each leg of chair makes contact with the floor in a circle that is 1.30cm in diameter. Find the pressure exerted on the floor by each leg of the chair, assume the weight is evenly distributed.
Q. Three equal point charges, each with charge 1.35 mu C, are located at the vertices of an equilateral triangle whose sides are of length 0.60m. What is an electric potential energy U of the system? (Take as zero the potential energy of the three charges when they are infinitely far apart.)