Determine the magnitude of the average friction force exerted on the collar when the velocity of the collar at C is 3.39 m/s and the spring has an unstretched length of 0.60 m .

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?