Answer:
[tex]v=\sqrt{2gL}[/tex]
Explanation:
mass of bob = M
string is fixed at C, at position A the string is horizontal and at position B teh string is vertical.
Let the length of the string is L.
At the point C, it has maximum potential energy which is equal to
U = M x g x L ..... (1)
At the position B, it has maximum kinetic energy and the velocity is v.
K = 1/2 Mv² ...... (2)
According to the conservation of energy
The potential energy at the position A is equal to the kinetic energy at position B.
M x g x L = 1/2 M x v²
v² = 2 x g x L
[tex]v=\sqrt{2gL}[/tex]
