A disc of radius r is connected to a string of length L. The string is tied to a point on the circumference of the disc. This system is made to oscillate in vertical plane of the disc with a small angular amplitude `theta_(0)`. Find the speed of the lowest point of the disc at the moment the string become vertical.

Answer

`theta_(0)(L+2r)sqrt((2g(L+r))/(r^(2)+2(L+r)^(2)))`