You Stand on a bathroom scale inside an elevator, press the button to go up and
ID: 1408666 • Letter: Y
Question
You Stand on a bathroom scale inside an elevator, press the button to go up and watch your weight change. During the first 15 seconds after you pressed the button your apparent weight is 170 ibs, then for the next 15 seconds your apparent weight is equal to your true weight of 160 Ibs. Full points will be awarded for the correct answer to the following question: What total distance did the elevator travel within these 30 seconds? Partial credit will be awarded for the correct answers to the following questions: What is the acceleration of the elevator during the 1^st 15-second interval? How far did the elevator travel during this 1^st 15-second interval? How fast was the elevator moving at the end of this 1^st 15-second interval? What is the acceleration of the elevator during the 2^nd 15-second interval? How far did the elevator travel during this 2^nd 15-second interval? How fast was the elevator moving at the end of this 2^nd 15-second interval? What total distance did the elevator travel within these 30 seconds?Explanation / Answer
True weight = 160 lbs = 72.64 kg
apparent weight N =m(a+g)
(170 * 0.454 * 9.8 ) = 72.64 ( a + 9.8)
a = 0.6125 m/s^2
for first 15 sec ,
(i) a = 0.6125 m/s^2
(ii) d = ut + at^2/2 = 0 + 0.6125*15^2 /2 = 68.9 m
(iii) v = u + at = 0 + 0.6152*15 = 9.19 m/s
(iv) a = 0
v) d2 = vt = 9.19 * 15 = 137.8 m
vi) a = 0 hence velocity will be constant
v = 9.19 m/s
total distance = d1+ d2 = 206.7 m
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