As shown in the figure, the wood block a & nbsp; and B & nbsp; are connected by a light spring and placed vertically on the wood block C & nbsp; with their mass ratio of 1:2:3. Suppose that all the contact surfaces are smooth, and the acceleration of the wood block a & nbsp; and B & nbsp; is & nbsp; () A. aA=0B. aA=gC. aB=3gD. aB=32g

As shown in the figure, the wood block a & nbsp; and B & nbsp; are connected by a light spring and placed vertically on the wood block C & nbsp; with their mass ratio of 1:2:3. Suppose that all the contact surfaces are smooth, and the acceleration of the wood block a & nbsp; and B & nbsp; is & nbsp; () A. aA=0B. aA=gC. aB=3gD. aB=32g

Before pulling out block C, block a is subjected to gravity and supporting force, f = Mg & nbsp; & nbsp; & nbsp; & nbsp; ① block B is subjected to gravity of 2mg, downward spring force F and supporting force n of block C. according to the equilibrium conditions, there are: n = f + Mg & nbsp; & nbsp; & nbsp; & nbsp; & nbsp; & nbsp; & nbsp; & nbsp; ② solution N = 3mg, remove block C