question_answer

Two blocks of masses 2.9 kg and 1.9 kg are suspended from a rigid support S by two inextensible wires each of length 1 m (figure). The upper wire has negligible mass and the lower wire has a uniform mass of 0.2 kg/m. The whole system of blocks, wires and support have an upward accelration of \[0.2\,m/{{s}^{2}}\]. The tension at the mid-point of the upper wire is

A)  20 N                                     

B)  30 N  

C)  40 N                     

D)  50 N

Correct Answer: D

Solution :

                 The tension at A                                 \[=({{m}_{1}}+{{m}_{2}})\,(g+a)\]                                 \[=(2.9+1.9)(9.8+2)\]                                 = 50 N