A force `F=-K(yhati+xhatj)` (where K is a positive constant) acts on a particle moving in the x-y plane. Starting from the origin, the particle is taken along the positive x-axis to the point `(a, 0)`, and then parallel to the y-axis to the point `(a, a)`. The total work done by the force F on the particle is

Options

A. `-2ka^(2)`
B. `2ka^(2)`
C. `-ka^(2)`
D. `ka^(2)`

Answer

B

Explanation

The mass of the hanging part = `m_(1) = m(l)/(n)`
[m = mass per unit length of chain]
The mass of section on tablen = `m_(2) = m (l-(l)/(n))`
For the chain to just move, `m_(1)g = T = F = mu m_(2)g`.
`implies m((l)/(n))g=muml(1-(l)/(n))gimplies mu = (1)/(n-1)`