Discuss ideas about how to create a speaker using electromagnets

Plss anybody know how to do this? ? i need the answers from a through d

A200-n force is applied to the foot-operated air pump. the return spring s exerts a 2.6-n·m moment on member oba for this position. determine the corresponding compression force c in the cylinder bd. if the diameter of the piston in the cylinder is 40 mm, estimate the air pressure generated for these conditions. state any assumptions. enter a positive number for the compression force c.

Which system of units is used by only a small number of countries in the world, including the u. s.