An Olympic weight lifter lifts a 186 kg weight from the floor to a height of 2.10 m.The change in the potential energy of the weight is

Question

Quizplus · Accepted Answer

The potential energy (PE) formula is PE = mgh, where m is the mass, g is the acceleration due to gravity, and h is the height. 
Converting 186 kg to Newtons, we have F = ma = 186 kg x 9.81 m/s² = 1824.66 N. 
Work = force x distance, so W = (1824.66 N)(2.10 m) = 3832 J. 
The change in potential energy is equal to the work done on the weight, so the answer is D, 3832 J. 
Note that the negative signs in choices A and C are incorrect, as the weight is being lifted, so the potential energy is increasing, not decreasing. Choice E is not equal to the work done on the weight. Choice B is not the correct answer, as it only gives the work done against gravity, not the total work done.

An Olympic Weight Lifter Lifts a 186 Kg Weight from the Floor