Block A of mass 2M hangs from a cord that passes over a pulley and is connected to block B of mass 3M that is free to move on a frictionless horizontal surface. The pulley is a disk with frictionless bearings, having a radius R and moment of inertia 3MR^2. Block C if mass 4M is on top of block B. The surface between blocks B and C is NOT frictionless. Shortly after the system is released from rest, block A moves with a downward acceleration a and the two blocks on the table move relative t each other
vertical tension in rope on right of pulley = 2Mg-2Ma
horizontal tension on rope on left of pulley = 2Mg-5Ma
Q: if a (linear accel) = 2m/s^2 determine the coefficient of kinetic friction between blocks B and C
static friction is less than or equal to coefficient of static multiplied by Fnormal
kinetic F = kinetic coefficient multiplied by Fnormal
The Attempt at a Solution
i played around with a number of things but really have no clue what im doing.
i wrote down the idea that the horizontal tension which was found to be 2mg-5ma must be more than the maximum static friction. then I isolated blockc (4M) and found the normal force to be 4MG ( i think) but i cannot figure out where the kinetic frictional force is acting since the both blocks are moving. AP exam on monday. its killing me that i can't get this. PLEASE HELP!!!