Return to Blackboard Cutnell, Physics, 10e BACK Focus on Concepts, Question 16 E

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Return to Blackboard Cutnell, Physics, 10e BACK Focus on Concepts, Question 16 E.im2 +mh-1080kg)(190m/s)2+188 Okg) 980m/s2 (55.0 m) Correct. The total mechanical energy is the kinetic energy plus the gravitational potential energy: Since friction and air resistance are being ignored, the total mechanical energy is conserved, which means that it has the same value, no matter what the height above sea level is. A bicycle nider has a speed of 19.0 m/s at a height of 55.0 m above sea level when he begins coasting down hill. The mass of the rider and his bike is 88.0 kg. Sea level is the zero level for measuring gravitational potentisli energy. Ignoring friction and air resistance, whot is the rider's total mechanical energy when he coasts to a height of 25.0 m above sea level 27 4.74 x 10) 418x 104 1.59× 10 · 633x104 , tudy Click·r you would like to show work for this question, open Show work

Explanation / Answer

intial mechanical energy at height h1 = 55 m Ei = PE + KE

potential energy PE = m*g8h1 = 88*9.8*55 = 47432 J

kinetic energy KE = (1/20*m*v1^2 = (1/2)*88*19^2 = 15884 J

total emchanical energy E = 47432 + 15884 = 6.33*10^4 J

from law of conservation of energy total mechanical energy is conserved

mechanical energy at heoght h2 ( 25 m) = mechanical energy at heoght (h = 55 m) = 6.33*10^4 J

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