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$2)$ An elevator is accelerating upward at a rate of $3\mathrm{.}6$ m$/$s $.$ A block of mass $23$ kg hangs by a low$-$mass rope from the ceiling, and another block of mass $70$ kg hangs by a low$-$mass rope from the upper block.

$($a$)$ What are the tensions in the upper and lower ropes?

$($b$)$ What are the tensions in the upper and lower ropes when the elevator accelerates downward at a rate of $3\mathrm{.}6$ m$/$s $?$