A bob of mass `m` hangs from the ceiling of a smooth trolley car which is moving with a constant acceleration a. If Young's modulus, radius and length of the string are `Y, r` and `l`, respectively, find the
(a) stress in the string and
(b) extension of the string when it makes a constant angle relative to the vertical.

Explanation

`a.(msqrt(g^(2)+alpha^(2)))/(pi r^(2))`
`b.(msqrt(q^(2)+alpha^(2)))/(pi r^(2)gamma)`