The $2400$ kg tractor A shown moves at a constantvelocity v $=6$ 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 $=8$ m$.$ When x $=$ 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 $=$ h$/2.$ Take g $=9\mathrm{.}8$ m$/$s$^2,$ and assume the pulleys to be ideal and small. $(5+8+5$