Problem

The potential energy

\phi

in joule of a particle of mass 1 kg moving in

x

y

plane obeys the law,

\phi = 3x + 4y

. Here,

x

and

y

are in metres. If the particle is at rest at

(6\text{m}, 8\text{m})

at time 0, then the work done by conservative force on the particle from the initial position to the instant when it crosses the

x

-axis is a. 25 J b.

-25\text{ J}

c. 50 J d.

-50\text{ J}