I don't really understand the difference and the relation between work and kinetic energy. When you move an object a distance you do work (or does the object work?), what's the object's kinetic energy? Is the kinetic energy the work you've put in to the box all gathered up at the end of the distance given the box keeps moving when you stopped pushing the box? The box can't have kinetic energy if's stationary after I've pushed the box can it?
Sorry if it's unclear.
Answer
The kinetic energy is indeed the work you have done (assuming no change in potential energy), however this is also neglecting the effect of friction. In real life, the kinetic energy of the box is going to be constant if its moving at a constant velocity even if you are exerting a force on the box and hence doing work on the box. This is because in this case, the work you are doing is being converted into heat and sound due to friction. If we neglect friction, your box would keep accelerating as you applied a force and hence the kinetic energy would keep increasing.
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