Two blocks are tied together with a massless string. A hand is used to lift one block so that both speed up while moving upward. Block A has a mass of $300$ g and block B has a mass of $500$ g$.$

d$)$ Calculate the magnitudes of all the forces in your diagrams for the case where the acceleration of block A has a magnitude of $4$ m$/$s$2.$

e$)$ How does the magnitude of the force that the string exerts on block A compare to the weight of B$?$ Explain.