In a given displacement of a particle, its kinetic energy increases by 25 J while its potential energy decreases by 10 J. Determine the work of the nonconservative forces acting on the particle during this displacement. a. –15 J b. +35 J c. +15 J d. –35 J e. +55 J workdone by non-conservative force =change in mechanical energy =25-10 =15 Hence I expect the answer to be c, but it turns up to be a, what is the reason?