Three blocks are stacked on the floor. From the bottom of the stack to the top, their masses are m1 , m2 , and m3 , respectively, as shown on the diagram. When referring to the various forces, the subscripts i=1,2,3 of the blocks will be used, and f will be used to indicate the floor. Weights, if required, will be denoted with the corresponding subscript of the block as F g,i , for i=1,2,3 . The normal force exerted by object a on object b , if required, will be denoted as F n,ab for i=1,2,3,f , but ab . The force of kinetic friction exerted by object a on object b , if required, will be denoted as F k,ab for i=1,2,3,f , but ab . The force of static friction exerted by object a on object b , if required, will be denoted as F s,ab for i=1,2,3,f , but ab