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posted by  menggay on 8/11/2008 4:12:47 AM  |  status: Live  

thermo problem

Course Textbook Chapter Problem
Thermodynamics Engineering Thermodynamics M. David Burghardt 0-201-32740-6 chapter 3 3.6
Question Details:
A child (25-kg mass) is swinging on a play set. The swing’s rope is 2.3 m long. Determine (a) the change in potential energy from 0° with the vertical when the swing goes from 0° to an angle of 45° with the vertical; (b) the velocity when the swing reaches the 0° angle.

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posted by bradely(SME Mechan on 8/14/2008 5:10:10 AM  |  status: Live
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"tnx"
Response Details:
P.E=mghcosθ
m=25-kg
h=2.3m
θ=0 to 45
(P.E) 1=(25)(9.81)(2.3)cos0=564.1J
(P.E) 2=(25)(9.81)(2.3)cos45=399 J
Change in P.E,P.E=399-564.1=165.24 J
v=√2gh=√(2*9.81*2.3) =6.72 m/s
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posted by rooya on 9/15/2008 4:03:20 AM  |  status: Live
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