In position A kinetic energy of a particle is 60 J and potential energy is -20 J. In position B, kinetic energy is 100 J and potential energy is 40 J. Then, in moving the particle from A to B

Options

A. work done by conservative forces is 50 J
B. work done by external forces is 40 J
C. net work done by all the forces 40 J
D. net work done by all the forces 100 J

Answer

C

Explanation

(c ) Work done by conservative forces`=U_(i)-U_(f)`
`=-20-40=-60J`
Work done by external forces`=E_(f)-E_(i)=140-40=100J`
and net work done by all the forces`=K_(f)-K_(i)`
`=100-60=40J`