Under certain circumstances, potassium ions (K ) in a cell will move across the 8.15 nm thick cell membrane from the inside to the outside. The potential inside the cell is -80.5 mV and the potential outside is zero. What is the change in the electrical potential energy of a single potassium ion as it moves across the membrane?Does the potential energy of the potassium ions increase, decrease, or remain the same as the ions move from the inside to the outside?

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.