Issac has to do 1000J of work on a 5kg box, and all the work he did simply went into lifting it above the ground. How high above the ground will the box be when all the work has been done?

Answer 1

You know that kinetic energy is 1/2*mass of box*velocity squared and that potential energy is mass of box*gravity*height. Conservation of energy says that kinetic energy initial plus the initial potential energy = final kinetic energy plus initial potential energy. you set your 1000J equal to your mass of box*g*h. you should is 1000J = 5*9.81*h
to get h you have to divided your 1000J by 5*9.81. The answer should be 20.39 meters.