Q. Two small metallic spheres, each of mass m = 0.25 g are suspended as pendulums by light strings from a common point. The spheres are given the same electric charge Q and it is found that they come to equilibrium when each string is at an angle of 5.0 with the vertical. Each string is 30.0 cm long.
Q. (a) A box sits at a rest on a rough 30 degree inclined plane. Draw the free-body diagram, showing all the forces acting on the box. (b) How would the diagram change if the box were sliding down the plane? (c) How would it change if the box were sliding up the plane after and initial shove?