Question

Design a "bungee jump" apparatus for adults

. A bungee jumper falls from a high platform with two elastic cords tied to the ankles. The jumper falls freely for a while, with the cords slack. Then the jumper falls an additional distance with the cords increasingly tense. Assume that you have cords that are 11 m long, and that the cords stretch in the jump an additional 23 m for a jumper whose mass is 140 kg, the heaviest adult you will allow to use your bungee jump (heavier customers would hit the ground).

a). Make a series of simple diagrams, like a comic strip,showing the platform, the jumper, and the two cords at varioustimes in the fall and the rebound. On each diagram, draw and labelvectors representing the forces acting on the jumper, and thejumper's velocity. Make the relative lengths of the vectors reflecttheir relative magnitudes

(b). At what instant is there the greatest tension in thecords? How do you know?

(c). What is the jumper's speed at this instant?

(d). Is the jumper's momentum changing at this instant or not?(That is, is dp/dt non-zero, or zero?) Explain briefly.

(e). Focus on this instant, and use the principles of thischapter to determine the spring's stiffness k(sub-s) for each cord.Explain your analysis. Give numerical values for yourdesign.

(f). What is the maximum tension that each cord must supportwithout breaking?

Give numerical values for your design.

(g). What is the maximum acceleration ("g's") that the jumperexperiences?

What is the direction of this maximum acceleration?

(h). State clearly what approximations and estimations youhave made in your design.

Answer 1