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Unformatted text preview: Sec_2.8-2.12.qxd 220 9/25/08 11:44 AM Page 220 CHAPTER 2 Axially Loaded Members Solution 2.8-11 Bumper for a mine car k 1120 lb/in.
7 mph g W 3450 lb 123.2 in./sec 32.2 ft/sec2 max of the spring. KINETIC ENERGY JUST BEFORE IMPACT
2 KE Wv2
2g Solve for Wv2
A gk ; A (386.4 in./sec2) (1120 lb/in.) SUBSTITUTE NUMERICAL VALUES:
dmax STRAIN ENERGY WHEN SPRING IS FULLY COMPRESSED
U U 386.4 in./sec2 Find the shortening KE Conservation of energy kd2
2 Problem 2.8-12 A bungee jumper having a mass of 55 kg leaps
from a bridge, braking her fall with a long elastic shock cord having
axial rigidity EA 2.3 kN (see figure).
If the jumpoff point is 60 m above the water, and if it is desired to
maintain a clearance of 10 m between the jumper and the water, what
length L of cord should be used? (3450 lb) (123.2 in./sec)2 11.0 in. ; ...
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This note was uploaded on 12/22/2011 for the course MEEG 310 taught by Professor Staff during the Fall '11 term at University of Delaware.
- Fall '11