### Assumption

I am a research and teaching assistant at the Swiss Federal Institute of
Technology in Zurich, Switzerland. Just recently, we corrected the written
exams of about 160 first-year physics students. One of the exam problems
consisted in calculating the length of a bungee cord so that the jumper
would just touch the water at the foot of the tower, given the height
of the platform, the jumper's mass and the strength of the cord.

The answer of one of the students started with the following sentence:
"For simplicity, I will neglect gravity in this problem."