Q : Two blocks of mass 2.9 kg and 1.9 kg are suspended from a rigid support S by two inextensible wires each of length 1 m, as shown in the figure. The upper wire has negligible mass and the lower wire has a uniformly distributed mass of 0.2 kg. The whole system of blocks, wire and support have an upward acceleration of 0.2 m/s². Acceleration due to gravity is 9.8 m/s². Find the tension at the mid-point of the upper wire.
(a) 50 N
(b) 80 N
(c) 90 N
(d) None of these
Ans: (a)
$ \displaystyle T – (2.9+1.9+0.2)g = (2.9+1.9+0.2) a $
$ \displaystyle T – 5 g = 5 a $
$\displaystyle T = 5(g + a) $
$ \displaystyle T = 5(9.8 + 0.2) = 5 0 N $