The $2400$ kg tractor A shown moves at a constant

velocity $v=6\frac{m}{s}$ to the right to vertically lift the

box B of mass $100$ kg using light inextensible ropes

moving over the ceiling pulley at a height $h=8m.$

When $x=\frac{h}{2},($a$)$ determine the acceleration of

the box B $,$ and $($b$)$ calculate the net friction force

developed between the powered rear wheels of the

tractor and the ground assuming no slip at the

contact. $($c$)$ Neglecting losses, calculate the power

developed by the tractor engine during this lifting

process when $x=\frac{h}{2}.$ Take $g=9\mathrm{.}8\frac{m}{s^2},$ and

assume the pulleys to be ideal and small. $(5+8+5)$