The drawing shows a set of equipotential surfaces seen in cross-sections. Each is labeled according to its electric potential. A 1.8 x 10-7 C point charge is placed at position A. Find the work done on the point charge by the electric force when it is moved (a) from A to B, and (b) A to C.

A5 foot by 5 foot box culvert is buried 6 feet beneath the surface of the ground. a crosssection of this very long culvert (into and out of the page) is illustrated below. assume that the soil in which the culvert is buried has the following properties: jt = 120 pcf, w = 12%, ko = 0.50, ka = 0.33, and kp = 3.00. calculate the total horizontal force per unit length of culvert (fh) felt on one of the vertical faces of the culvert.