Which equation represents the law of conservation of energy in a closed system?

KEi + PEi = KEf + PEf
PEi + PEf = KEi + KEf
KEi – KEf = PEi – PEf
KEi – PEf = PEi – KEf

Explanation:

A closed system is a system where exists energy interactions with surroundings, but not mass interactions. If we neglect any energy interactions from boundary work, heat, electricity, magnetism and nuclear phenomena and assume that process occurs at steady state and all effects from non-conservative forces can be neglected, then the equation of energy conservation is reduce to this form:

(1)

Where:

- Change in kinetic energy of the system, measured in joules.

- Change in gravitational potential energy of the system, measured in joules.

If we know that and , then we get the following equation:

(2)

Where and stands for initial and final states of each energy component.

Hence, the right answer is

the answer would be 32*f

the box does not move because you need to use a force greater than 300 n. you are only using 50 n. it needs to at least be 301 n for the box to move because then it is an unbalanced force and it will move the way that the greater force is pushing it. if you use only 300 n it will be a balanced force and will not move because the force you are exerting on the   box is the same as its force.

hope this !

im sorry if i went too in depth, i am going to include a link to a video on khan academy that will explain this.   hope that you like the video and that it explains more in detail to you.

that is the link.