Which of the following is not an example of work? 1.a man pushing a heavy box across the floor
2.an air hockey puck traveling at a constant speed
3.a magnet repelling a 4.compass needle
ship movement that causes ripples in the water

Students in an introductory physics lab are performing an experiment with a parallel-plate capacitor made of two circular aluminum plates, each 11 cm in diameter, separated by 1.0 cm. how much charge can be added to each of the plates before a spark jumps between the two plates? for such flat electrodes, assume that value of 3×106n/c of the field causes a spark.