CFS Metric & Imperial Conversion 3 — Questions and Answers
Question 1: What is the tensile stress area of an M12×1.75 bolt in mm²? (Use the formula: As = 0.7854 × (d - 0.9743/n)²)
- 84.3 mm² (Correct answer)
- 113.1 mm²
- 76.2 mm²
- 92.1 mm²
Correct answer: 84.3 mm²
For M12×1.75 the standard tensile stress area is 84.3 mm² per ISO 898 tables.
Question 2: Convert a clamping force of 10,000 N to pound-force (lbf).
- 2,248 lbf (Correct answer)
- 1,000 lbf
- 4,536 lbf
- 9,807 lbf
Correct answer: 2,248 lbf
1 N = 0.2248 lbf, so 10,000 N × 0.2248 = 2,248 lbf.
Question 3: A 3/8-16 UNC bolt has a pitch of how many millimeters?
- 1.588 mm (Correct answer)
- 1.270 mm
- 2.117 mm
- 0.794 mm
Correct answer: 1.588 mm
Pitch = 25.4 ÷ TPI = 25.4 ÷ 16 = 1.5875 mm ≈ 1.588 mm.
Question 4: An engineer specifies a surface finish of 1.6 μm Ra. What is the approximate equivalent in microinches (μin)?
- 63 μin (Correct answer)
- 32 μin
- 125 μin
- 16 μin
Correct answer: 63 μin
1 μm = 39.37 μin, so 1.6 μm × 39.37 ≈ 63 μin.
Question 5: A nut has a width-across-flats of 19 mm. Which standard inch wrench size is the closest fit?
- 3/4 inch (19.05 mm) (Correct answer)
- 11/16 inch (17.46 mm)
- 13/16 inch (20.64 mm)
- 5/8 inch (15.88 mm)
Correct answer: 3/4 inch (19.05 mm)
19 mm is nearly identical to 3/4 inch (19.05 mm), making it the closest standard inch wrench.
Question 6: A fastener's shear strength is listed as 90,000 psi. What is this in ksi?
- 90 ksi (Correct answer)
- 900 ksi
- 9 ksi
- 0.090 ksi
Correct answer: 90 ksi
1 ksi = 1,000 psi, so 90,000 psi ÷ 1,000 = 90 ksi.
Question 7: Convert 8.8 mm bolt grip length to the nearest 1/16 inch increment.
- 11/32 inch (8.73 mm) (Correct answer)
- 3/8 inch (9.53 mm)
- 5/16 inch (7.94 mm)
- 7/16 inch (11.11 mm)
Correct answer: 11/32 inch (8.73 mm)
8.8 mm ÷ 25.4 = 0.346 in; the nearest 1/16-inch increment is 11/32 in (0.344 in = 8.73 mm).
CFS Metric & Imperial Conversion 3
What is the tensile stress area of an M12×1.75 bolt in mm²? (Use the formula: As = 0.7854 × (d - 0.9743/n)²)