Deepak Patra
Last Activity: 10 Years ago
The correct option is:
The figure below shows the free body diagram of the bird-string system, the forces acting on the bird and the stretched string. Assume that W represents the magnitude of weight of the bird, θrepresents the angle of the rope with horizontal whereas T represents the magnitude of tension in the string.

If there is no horizontal or vertical motion of the bird and string, the forces along in the horizontal direction and in the vertical direction must individually sum to zero.
That is,
T cos θ = T cos θ
2T sin θ = W
From the second equat6ion, we have
2T sin θ = W

For, values of sin θ lying between 0 and 1, the tension in the rope will always be greater than W/2, but it can never exceed W.
Therefore (b) is the correct option while the others are ruled out.