Q. The leg and cast weigh 220 N, with the center of mass as indicated by the blue arrow in the diagram. The counterbalance w1 weighs 135 N. Determine the weight w2 and the angle α needed so that no force is exerted on the hip joint by the leg plus cast.
Q. A metal plate with total charge of -160 nC has dimensions 2 m x 2 m and negligible thickness. (a) Find the surface charge density of the plate. (b) Calculate the electric field at distance of 10 cm* from the plate's center? (c) Draw the electric field (lines) around the plate. (d) An electron is shot against the plate from a distance of 10 cm and just manages to reach it. Find the initial velocity of the electron.