To add to the festivities during Homecoming Week, Knightro is dropping 0.5 kg water balloons from a second story window (about 10 m above the sidewalk) onto unsuspecting students as they walk to their physics class. After a near miss, one student decides to analyze the mechanical energy of the water balloons; the student chooses the sidewalk as her reference point. Knightro is also interested in physics, and decides to do a similar analysis, with the second floor level as his reference point.

a. For her calculations, the student chooses the initial height of the water balloon as 10 m and the final height when it barely misses her to be 0 m. What does the student calculate as the initial potential energy of the balloon?