A uniform rod of mass M and length L, area of cross section A is placed on a smooth horizontal surface. Forces acting on the rod are shown in the digram

Ratio of elongation in section PQ of rod and section QR of rod is

Options

A. `1:1`
B. `3:5`
C. `5:7`
D. `1:2`

Explanation

`Deltal_(1)=((3F)/2)(L/2)/(2AY)+(FL/2)/(2AY)=(5FL)/(8AY)`
`Deltal_(2)=(2FL/2)/(2AY)+((3F)/2L/2)/(2AY)=(7FL)/(8AY)`
`(Deltal_(1))/(Delta_(2))=5/7`