(10%) Problem 4: Near the top of the Citigroup Center building in New York City,
ID: 1572850 • Letter: #
Question
(10%) Problem 4: Near the top of the Citigroup Center building in New York City, there is an object with mass of 3.2 × 105 kg on springs that have adjustable force constants. Its function is to dampen wind-driven oscillations of the building by oscillating at the same frequency as the building is being driven-the driving force is transferred to the object, which oscillates instead of the entire building 50% Part (a) What effective force constant, in N/m, should the springs have to make them oscillate with a period of 1.2 s? Grade Summary Deductions Potential 0% 100% Submissions Attempts remaining: 10 (1% per attempt) detailed view sin coS tan() cotan0 asin0 4 5 6 acos atan0acotan)sinhO cosh0 tanh0 cotanh0 0 END Degrees Radians DEL CLEAR Submit Hint I give up! Hints: 1 % deduction per hint. Hints remaining: 2 Feedback: 0% deduction per feedback. Submission History Answer Hints Feedback Totals Totals 0% 0% 0% 0% Glà 50% Part (b) What energy, in joules, is stored in the springs for a 1.2 m displacement from equilibrium?Explanation / Answer
w=sqrt(k/m)
period=2*pi/w
period=2*pi*sqrt(m/k)
1.2=2*pi*sqrt(3.2*10^5/k)
we got
k=8.77*10^(6) N/m
(b) Energy=0.5*k*x^2
Energy=6.3*10^6 J
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