Two long wires are oriented so that they are perpendicular to each other, and at their closest they are 20.0 cm apart. what is the magnitude of the magnetic field at a point midway between them if the top one carries a curent of 25.6 a and the bottom one carries 5.4 a?

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.