A rod of length L and mass M is acted on by two unequal force F1 and F2 (< F1) as shown in fig.
The tension in the rod at a distance x from end B will be
Net force on the rod = F1 - F2
Now consider t}re motion of part BC. Mass of this part = (M / L) x. Then
where I is the tension at point C. So
.