A block of mass `1kg `is placed on a rough horizontal surface. A spring is attached to the block whose other end is joined to a rigid wall, as shown in the figure. A horizontal force is applied on the block so that it remains at rest while the spring is elongated by `x(xge(mumg)/(k))`. Let `F_(max)` and `F_(mi n)` be the maximum and minimum values of force `F` for which the block remains in equilibrium. For a particular `x, F_(max)-F_(mi n)=2N`. Also shown is the variation of `F_(max)+F_(mi n)` versus `x`, the elongation of the spring.

The spring constant of the spring is `:`

Options

A. `25N//m`
B. `20N//m`
C. `2.5N//m`
D. `50N//m`

Answer

A

Explanation

`F_(max)+F_(min)=2kx ....(1)`
from graph `F_(max)+F_(min)=5`
and `x=0.1`
Putting in equation `(1)`
`t=2k(0.1)`
`k=25N//m`.