Question

An object of mass 4kg initially at rest on a surface has both kinetic and potential energies equal to zero. It is then lifted

under the influence of both nonconservative forces and the conservative force of gravity. The nonconservative forces do +40J
of work on the object. The conservative force does -22J of work.

The potential energy of the object after the motion is
(A) 0J
(B) +18J
(C) +22J
(D) +40J
(E) +62J

Answer 1

Using the work-energy principle, the potential energy of the object after the work done by both nonconservative and conservative forces is +18J.

The problem involves the concept of energy conservation where the work done by nonconservative and conservative forces will determine the final potential energy of the system. An object of mass 4kg is initially at rest and then subjected to +40J of work by nonconservative forces and -22J of work by the conservative force of gravity. According to the work-energy principle, which states KEi + PEi + Wnc = KEf + PEf, the final potential energy of the object can be determined by summing the work done by both types of forces. Considering that the object started with zero potential energy, the nonconservative work will increase its mechanical energy, while the work by gravity will decrease it.

In this case, the final potential energy (PEf) can be calculated as:

PEf = PEi + Wnc + Wc

PEf = 0J + 40J + (-22J)

PEf = 18J

Therefore, the potential energy of the object after the motion is +18J (Option B).

Answer 2

(B) +18J

I found it similarly to how i find resultant forces in general… but i am not sure