The force exerted by an electric charge at the origin on a charged particle at a point (x, y, z) with position vector r = x, y, z is f(r) = kr/|r|3 where k is a constant. find the work done as the particle moves along a straight line from (4, 0, 0) to (4, 2, 3).

Consider a u-tube whose arms are open to the atmosphere. now equal volumes of water and light oil (ρ = 49.3 lbm/ft3) are poured from different arms. a person blows from the oil side of the u-tube until the contact surface of the two fluids moves to the bottom of the u-tube, and therefore, the liquid levels in the two arms are the same. if the fluid height in each arm is 30 in, determine the gage pressure exerted by the person on the oil by blowing.