A bob of mass ' m ' is suspended by a light inextensible string of length ' ℓ ' from a fixed point such that it is free to rotate in a vertical plane. The bob is given a speed of 4

Question

A bob of mass ' m ' is suspended by a light inextensible string of length ' ℓ ' from a fixed point such that it is free to rotate in a vertical plane. The bob is given a speed of 4 g ℓ ​ horizontally where ℓ = 3 m . Find the height (in m) of the bob from the lower most point where the string just becomes slacked.

TestHub · Accepted Answer

u = 4 g l ​ 2 1 ​ m u 2 = 2 1 ​ m v 2 + m g h ⇒ v 2 = 4 g l − 2 g h T = 0 l v 2 ​ = g ( 1 − cos θ ) h = l ( 1 − cos θ ) l 4 g l − 2 g h ​ = g h ⇒ 4 g − l 2 g h ​ = l g h ​ h = 3 5 l ​ l = 3 m ⟹ h = 5 m

Physics - W.E.P. Question with Solution | TestHub

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