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https bbprod.stjohns.edu/bbcswebdav/pid-1423 147-dt-content-rid-922 3659_1 /courses 00C-0-75236-2 https:/ /bb PART Il: 10 Open Ended Problems. All of the questions must be answered in this Exam. (6 pts each, 60 pts. Total). Show all work to require credit for these problems. 21. A 65-kg pole vaulter wishes to vaultto a height a 5.5 meters. (a) Calculate the minimum amount of kineticenergy the vaulter needs to reach this height ifair friction is neglected and all the vaulting energy is derived from Kinetic Energy. (b) Calculate the speed the given vaulter must attain to have the necessary kinetic energyExplanation / Answer
a) Apply conservation of energy
KEi = PEf
KEi = m*g*h
= 65*9.8*5.5
= 3504 J
b) KEi = (1/2)*m*vi^2
==> vi = sqrt(2*KEi/m)
= sqrt(2*3504/65)
= 10.4 m/s
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