When the three blocks are released from rest, they accelerate with a magnitude of 0.660 m/s2. Block 1 has mass M, block 2 has 4M, and block 3 has 4M. What is the coefficient of kinetic friction between block 2 and the table? (this is a pulley system where block 1 and 3 are hanging from pulleys off the table and are connected to block 2 which is on the table)