Force conversion: choose the equivalent value of one newton (N) expressed in kilogram-force (kgf).
Civil Engineering
SI Units
Difficulty: Easy
Choose an option
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A0.10197 kgf
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B0.20197 kgf
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C9.80665 kgf
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D0.97125 kgf
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E0.00981 kgf
Answer
Correct Answer: 0.10197 kgf
Explanation
Introduction / Context:Although the S.I. unit of force is the newton, legacy engineering literature frequently uses kilogram-force (kgf). Knowing the exact relationship helps convert test data, nameplate values, and historical problems to S.I. without confusion.
Given Data / Assumptions:
- 1 kgf is defined as the weight of a 1 kg mass under standard gravity g0 ≈ 9.80665 m/s^2.
- Therefore 1 kgf = 9.80665 N.
- We seek 1 N in kgf.
Concept / Approach:Use the reciprocal relationship: if 1 kgf = 9.80665 N, then 1 N = 1 / 9.80665 kgf ≈ 0.10197 kgf. Precision to five significant digits is common in standards and is more than sufficient for most calculations.
Step-by-Step Solution:
Start with: 1 kgf = 9.80665 N.Invert both sides: 1 N = 1 / 9.80665 kgf.Compute: 1 / 9.80665 ≈ 0.10197 kgf.Verification / Alternative check:
Cross-check the inverse: 0.10197 kgf * 9.80665 N/kgf ≈ 1.00000 N (rounding error only).Why Other Options Are Wrong:
0.20197 kgf and 0.97125 kgf: inconsistent with the exact reciprocal; far too large.9.80665 kgf: equals ~96.2 N, not 1 N.0.00981 kgf: off by a factor of ~10.Common Pitfalls:
Confusing mass (kg) with force (kgf); interchanging g and 1/g.Using 9.81 vs 9.80665 without tracking significant figures.Final Answer:
0.10197 kgf