Question

Please solve the problem based on the conservation of energy?

Answer 1

`d`

Explanation:

Conservative force means a force which brings a particle towards least value of potential energy.

But here in this system potential energy of the system is being increased,so work is being done against the conservative force.

So,some force(s) is(are) acting to increase the potential energy of the particle and that value is `40-(-20)=60J`

And that(those) force(s) is(are) also acting to increase kinetic energy,so work done by external force is `100-60 =40 J`

So,net work done by that force is `60+4=100 J` (this is the value which corresponds to net increase in total energy)