A particle of mass m is acted on by F ⃗ \vec{F} F =K[x î+y ĵ]/(x²+y² ) 3 2 )^{\frac32} ) 2 3 . It is moved from (a,0) to (0,a) along a circular path of radius a about the origin. The work done is:
Physics · Work , Power and Energy · conservative force and potential energy
JEE Advanced 2013

Question

A particle of mass m is acted on by F ⃗ \vec{F} F =K[x î+y ĵ]/(x²+y² ) 3 2 )^{\frac32} ) 2 3 . It is moved from (a,0) to (0,a) along a circular path of radius a about the origin. The work done is:

Physics · Work , Power and Energy · conservative force and potential energy

JEE Advanced 2013

G1 Physics · Accepted Answer

The force is purely radial, proportional to r̂/r². Along the circular path of radius a, every displacement element is tangential, so F⃗·dr⃗=0 at every point. Therefore the work is zero, option D.

A particle of mass m is acted on by F ⃗ \vec{F} F =K[x î+y ĵ]/(x²+y² ) 3 2 )^{\frac32} ) 2 3 ​ . It is moved from (a,0) to (0,a) along a circular path of radius a about the origin. The work done is:

A particle of mass m is acted on by F ⃗ \vec{F} F =K[x î+y ĵ]/(x²+y² ) 3 2 )^{\frac32} ) 2 3 . It is moved from (a,0) to (0,a) along a circular path of radius a about the origin. The work done is: