Awheel of diameter 8.0 cm has a cord of length 6.0 m wound around its periphery. starting from rest, the wheel is given a constant angular acceleration of 3.0 rad/s2. how long will it take the cord to unwind

Large electric fields in cell membranes cause ions to move through the cell wall. the field strength in a typical membrane is 1.0 x 10 7 n/c. what is the magnitude of the force on a calcium ion with charge +e? what is its acceleration? is it possible for a particle with the same charge as as calcium to have a different acceleration if placed at this location? what would change the acceleration: mass of the particle? diameter of the particle?