A heavy string of mass m hangs between two fixed points A and B at the same level. The tangents to the string at A and B are at an angle θ with the horizontal as shown in the figure. The tension in the string at the lowest point is
The correct option is C. mg2 tan θ.
From the free body diagram of the half part of the wire shown above we have,
In the vertical direction, T sin θ=mg/2 .............(i)
(Since the tension at one end balances the weight of the half part of the wire)
In the horizontal direction, T′=T cos θ ...........(ii)
From equation (i) and equation (ii) we get,
T′=mg2cot θ=mg2 tan θ.