A moving particle is acted upon by several forces `F_(1),F_(2),F_(3)`….etc. One of the force is chosen sat `F_(2)` the which of the following statement about `F_(2)` will be true.

Options

A. Work done by `F_(2)` will be negative if speed of the particle decreases
B. Work done by `F_(2)` will be positive if speed of the particle increases
C. Work done by `F_(2)` will be equal to the work done by other forces if speed of the particle does not change
D. If `F_(2)` is a conservative force, then work done by all other forces will be equal to change in potential energy due to force `F_(2)` when speed remains constant.

Answer

D

Explanation

By work energy theorem
`W_(F_(2))+W_("other") = Delta K`
`rArr W_(F_(2)) = Delta K - W_("other")`
So A & B are wrong
If speed do not change `Delta K =0`
then `W_(F2)=-W_("other")`...(1)
So `W_(F_(2))ne W_("other")`
If `F_(2)` is conservative force then
`Delta U = -W_(F_(2)) = W_("other") ("from" (1)`