Tom D. spends his spare time running a bungee jumping service off the Henley Str

Question

Tom D. spends his spare time running a bungee jumping service off the Henley Street bridge. He has a 127 ft long bungee cord (unstretched) that has a spring stiffness of 29 lb/ft. To test his bungee, he ties the bungee cord to the bridge railing, ties the other end to an unnamed professor weighing 132 pounds, and then gently nudges the professor off of the bridge. EXAMPLE NOTES IMAGES DISCUSS UNITS S STATSHELP Part Description Answer Chk History Determine the professor's speed when the bungee cord starts to stretch. (include units with answer) 25 pts, 100% # tries: 0 show Details Format Check 290 try penalty Hints: 1,0 Assuming he hasn't hit the water, how much has the bungee chord stretched when the professor is at the bottom of the jump? (include units with answer) 25 pts. 100% # tries: 0 show Details Format Check 290 try penalty

Explanation / Answer

a)

using conservation of energy

kinetic energy at the time of stretch = potential energy at top

(0.5) m v2 = mgh

v = sqrt(2 g h)

v = sqrt(2 x 32.2 x 127) = 90.4 ft/s

B)

at the bottom of the jump

Potential energy at The top = spring energy

mgh = (0.5) k x2

(132) (32.2) (127) = (0.5) (29) x2

x = 192.95 ft

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