M 52. A simple Atwood's machine remains motionless when equal masses M are placed on each end of the chord. When a small mass m is added to one side, the masses have an acceleration a. What is M? You may neglect friction and the mass of the cord and pulley. (A) 1 24 (B) 2m(+) (C) (D) 24 1 2 53. Block 1 is stacked on top of block 2. Block 2 is connected by a light cord to block 3, which is pulled along a frictionless surface with a force F as shown in the diagram. Block 1 is accelerated at the same rate as block 2 because of the frictional forces between the two blocks. If all three blocks have the same mass m, what is the minimum coefficient of static friction between block 1 and block 2? (A) 2F/mg (B) F/mg (C) 3F/2mg (D) F/3mg m3 m2 m1 7777 54. Three blocks (my, my, and my) are sliding at a constant velocity across a rough surface as shown in the diagram above. The coefficient of kinetic friction between each block and the surface is p. What would be the force of my on m₂? (A) (m+m)gu (B) F-(m-m)gu (C) F (D) mgu-(m,+ m)gu