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posted by  jlswack on 9/16/2008 12:14:04 AM  |  status: Live  

Motion in Accelerated Frames

Course Textbook Chapter Problem
Calculus Based Physics Physics For Scientists And Engineers 7th by Jewett, Serway 6 23
Question Details:
A person stands on a scale in an elevator. As the elevator starts, the scale has a constant reading of 598 N. Later, as the elevator later stops, the scale reading is 400 N. Assume the magnitude of the acceleration is the same during starting and stopping.
 
A) Determine the weight of the person in N.
 
B) Determine the mass of the person in Kg
 
C) Determine the acceleration of the person in m/s^2.
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posted by booboo123 on 9/16/2008 6:25:40 PM  |  status: Live
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jlswack's comment:
"Thank you so much"
Response Details:
When starting, W1 - mg = m.a
                      W1 = m(g +a) = 598 ----------(1)
When stopping, 
                     W2 = m(g - a) = 400 -------------(2)
Adding,                2mg = 598 +400 = 998
 
(a)         Weight, W = mg = 998/2 = 499 N
 
(b)          Mass, M = W/g = 499/9.8 = 50.9 kg
 
(c)          Subtracting,  2ma = 598 -400 = 198
             Acceleration, a = 198/ (2x50.9) = 1.94 m/s2

*cr to Kayen, I just put your numbers in for you :)
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