$**29.$ A cylindrical room is rotating fast enough that two small blocks stacked against the wall do not drop. The mass of block A is $4$ kg and that of block B is $3$ kg$.$

a$)$ Draw a diagram of the wall and of blocks A and B$.$ Indicate the direction of the acceleration of block B at the instant shown in the figure. If it is zero, state that explicitly.

b$)$ Draw separate free$-$body diagrams for blocks A and B and label the forces as described on page $85.$

c$)$ Identify any third$-$law companion forces on your diagrams using tick marks like those used in Example $6\mathrm{.}1.$

d$)$ Rank the magnitudes of all the horizontal forces that you identified above in order from largest to smallest. Explain your reasoning.

e$)$ Determine the magnitude of each of the vertical forces on block A$.$ If it is not possible to determine one of these, explain why not.