If V_ab is the potential difference across the resistive coil of resistance R, Pis the power input to the coil, E is the energy required to boil a cup of water, and t is the time needed to heat a cup of water using the electric device, which of the following quantities are known in this problem?a. tb. Rc. Vabd. Rinte. Ef. Ig. Ph. E

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.