A 12 g coin slides upward on a surface that is inclined at an angle of 15o above the horizontal. The coefficient of kinetic friction between the coin and the surface is 0.23; the coefficient of static friction is 0.31.
  1. Find the magnitude and direction of the force of friction.
  2. At what rate is the coin decelerating?
  3. After its velocity reaches zero, does the coin slide back down or remain at rest on the surface?
  4. If the incline angle changes to 25o does the coin remain at rest, or slide back down after reaching its highest point?