Substrate Record: qid 11794

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qid 11794 · engineering

Question: A steel helical spring of index 10 has 12 active coils. The spring is made of oil-tempered no. 7 gauge wire. Determine the fundamental frequency of the spring if (1) one end is fixed and one end is free. (2) both ends are fixed. For the first case, check for the safety of the spring against failure due to surging when the operating load frequency due to external excitation source is 120 cycles per minute. The specific weight of steel is y = 0.285 lb/in3 and acceleration due to gravity g = 386 in/sec. Modulus of rigidity for steel G = 11.5 × 10^6 lb/in^2.

1. 29 cycles/sec and 58 cycles/sec
2. 28 cycles/sec and 56 cycles/sec
3. 31 cycles/sec and 62 cycles/sec
4. 34 cycles/sec and 68 cycles/sec
5. 30 cycles/sec and 60 cycles/sec
6. 33 cycles/sec and 66 cycles/sec
7. 37 cycles/sec and 74 cycles/sec
8. 35 cycles/sec and 70 cycles/sec
9. 32 cycles/sec and 64 cycles/sec
10. 36 cycles/sec and 72 cycles/sec

Our answer: F. 33 cycles/sec and 66 cycles/sec Source quote machine-checked (exact quote)

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