A thin uniform rod of mass m moves translational with acceleration a due to two antiparallel forces of lever arm l. one force is of magnitude F and acts at one extreme end. The length of the rod is

Q: A thin uniform rod of mass m moves translational with acceleration a due to two antiparallel forces of lever arm l. one force is of magnitude F and acts at one extreme end. The length of the rod is

(a) $\frac{m a l}{m a + F}$

(b) $\frac{2 ( F + m a) l}{m a }$

(c) $ l (1 + \frac{F}{m a }) $

(d) $\frac{( F + m a) l}{2 m a }$

Ans: (b)