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.

The long handle on a rake is a(n) a. lever b. screw c. wedge d. inclined plane

Explain what happens at the saturation point when adding salt to water at room temperature.

Consider a double atwood machine constructed as follows: a mass 4m is suspended from a string that passes over a massless pulley on frictionless bearings. the other end of this string supports a second similar pulley, over which passes a second string supporting a mass of 3m at one end and m at the other. using two suitable generalized coordinates, set up the lagrangian and use the lagrange equations to find the acceleration of the mass 4m when the system is released. explain why the top pulley rotates even though it carries equal weights on each side.