Answer:
6370 J
Explanation:
By the law of energy conservation, the work done by the student would be the change in potential enegy from 1st floor to 3rd floor, or a change of 13 m

where m = 50kg is the mass of the student, g = 9.8 m/s2 is the gravitational constant and h = 13 m is the height difference

Answer:
It always acurs after a 1st quarter
do you have photo?
Explanation:
<span>Vibration waves from earth quakes travel through the earth and have measurable speed. And the different temperatures and fluidity of the various regions of the mantle will change that speed and or reflect the vibration waves in different directions. With multiple vibration sensors around the world the time that it takes for vibrations to travel from one part of the world to another will tell you what is inside.</span>