Aditi Chauhan
Last Activity: 10 Years ago
Sol. . At equilibrium ⇒ T = mg
When it moves to an angle θ, and released, the tension the T’ at lowest point is
⇒ T’ = mg + mv2/r
The change in tension is due to centrifugal force ∆T = mv2/r ….(1)
⇒ Again, by work energy principle,
⇒ 1/2mv2 – 0 = mgr(1 - cosθ)
⇒ v2 = 2gr (1- cosθ)
So, ∆T = m[2gr(1 – cos θ)]/r = 2mg(1 – cos θ)
⇒ F = ∆T
⇒ F = YA ∆L/L = 2mg – 2mg cos θ ⇒ 2mg cos θ = 2mg - YA ∆L/L
= cos θ = 1 - YA ∆L/L(2mg)