Screw Thread
Statics · FE Reference Handbook section
Core formulas for this FE topic
Definitions, applicability, units, assumptions and worked examples for each relation.
Worked exam-style examples
The four ways this section is written on the real exam — thoughts first, then equations, then substitution.
A statics problem uses Moment of a force. Given force (F) = 1,271 lb; moment arm (d) = 10.1000 ft, determine the moment (M) in lb·ft.
Given
Find
moment (M), in lb·ft
Start with the thinking
- The governing relation printed in this handbook section is Moment of a force.
- Everything except M is given, so isolate M symbolically first — never rearrange after the numbers are in.
- Tabulate each given with its unit and confirm the units are consistent with the relation before substituting.
- Statics items reward recognising the unknown before touching a calculator.
Step-by-step solution
Step 1 — State the governing relation:
Step 2 — Rearrange the relation so that M stands alone on the left-hand side.
Step 3
Step 4 — Substitute the given values into the rearranged relation.
Step 5 — Evaluate:
Step 6 — Check: returning M = 12,837 lb·ft to
reproduces the given quantities, and both sides carry the same units.
Why the other options are there
- 25,674 — kept a factor of two that cancels in the correct rearrangement.
- 6,419 — dropped that same factor in the other direction.
- 14,121 — rounded an intermediate value before the final step.
Reference: FE Reference Handbook — Statics → Screw Thread
A statics problem uses Coulomb friction. Given friction coefficient (mu) = 0.6100; normal force (N) = 1,006 lb, determine the friction force (F) in lb.
Given
Find
friction force (F), in lb
Start with the thinking
- The governing relation printed in this handbook section is Coulomb friction.
- Everything except F is given, so isolate F symbolically first — never rearrange after the numbers are in.
- Tabulate each given with its unit and confirm the units are consistent with the relation before substituting.
- Statics items reward recognising the unknown before touching a calculator.
Step-by-step solution
Step 1 — State the governing relation:
Step 2 — Rearrange the relation so that F stands alone on the left-hand side.
Step 3
Step 4 — Substitute the given values into the rearranged relation.
Step 5 — Evaluate:
Step 6 — Check: returning F = 613.7 lb to
reproduces the given quantities, and both sides carry the same units.
Why the other options are there
- 1,227 — kept a factor of two that cancels in the correct rearrangement.
- 306.8 — dropped that same factor in the other direction.
- 675.0 — rounded an intermediate value before the final step.
Reference: FE Reference Handbook — Statics → Screw Thread
a wrench applied to an anchor nut Given force (F) = 1,256 N; perpendicular distance (d) = 3.5000 m, determine the moment (M) in N\cdot m.
Given
Find
moment (M), in N\cdot m
Start with the thinking
- The governing relation printed in this handbook section is Moment of a force about a point.
- Everything except M is given, so isolate M symbolically first — never rearrange after the numbers are in.
- Tabulate each given with its unit and confirm the units are consistent with the relation before substituting.
- A force acting at a perpendicular distance d produces a moment.
Step-by-step solution
Step 1 — State the governing relation:
Step 2 — Rearrange symbolically for M:
Step 3
Step 4 — Substitute the given values:
Step 5 — Evaluate:
Step 6 — Check: returning M = 4,394 N\cdot m to
reproduces the given quantities, and both sides carry the same units.
Why the other options are there
- 8,789 — kept a factor of two that cancels in the correct rearrangement.
- 2,197 — dropped that same factor in the other direction.
- 4,834 — rounded an intermediate value before the final step.
Reference: FE Handbook — Statics (Moments)
A statics problem uses Moment of a force. Given moment arm (d) = 18.6000 ft; moment (M) = 7,733 lb·ft, determine the force (F) in lb.
Given
moment (M) = 7,733 lb·ft
Find
force (F), in lb
Start with the thinking
- The governing relation printed in this handbook section is Moment of a force.
- Everything except F is given, so isolate F symbolically first — never rearrange after the numbers are in.
- Tabulate each given with its unit and confirm the units are consistent with the relation before substituting.
- Statics items reward recognising the unknown before touching a calculator.
Step-by-step solution
Step 1 — State the governing relation:
Step 2 — Rearrange the relation so that F stands alone on the left-hand side.
Step 3 — List the givens: moment arm (d) = 18.6000 ft, moment (M) = 7,733 lb·ft.
Step 4 — Substitute the given values into the rearranged relation.
Step 5 — Evaluate:
Step 6 — Check: returning F = 415.8 lb to
reproduces the given quantities, and both sides carry the same units.
Why the other options are there
- 831.5 — kept a factor of two that cancels in the correct rearrangement.
- 207.9 — dropped that same factor in the other direction.
- 457.3 — rounded an intermediate value before the final step.
Reference: FE Reference Handbook — Statics → Screw Thread
A statics problem uses Coulomb friction. Given normal force (N) = 1,131 lb; friction force (F) = 196.0 lb, determine the friction coefficient (mu).
Given
Find
friction coefficient (mu)
Start with the thinking
- The governing relation printed in this handbook section is Coulomb friction.
- Everything except mu is given, so isolate mu symbolically first — never rearrange after the numbers are in.
- Tabulate each given with its unit and confirm the units are consistent with the relation before substituting.
- Statics items reward recognising the unknown before touching a calculator.
Step-by-step solution
Step 1 — State the governing relation:
Step 2 — Rearrange the relation so that mu stands alone on the left-hand side.
Step 3
Step 4 — Substitute the given values into the rearranged relation.
Step 5 — Evaluate:
Step 6 — Check: returning mu = 0.1733 to
reproduces the given quantities, and both sides carry the same units.
Why the other options are there
- 0.3466 — kept a factor of two that cancels in the correct rearrangement.
- 0.0866 — dropped that same factor in the other direction.
- 0.1906 — rounded an intermediate value before the final step.
Reference: FE Reference Handbook — Statics → Screw Thread
a bracket bolted to a column flange Given moment (M) = 5,304 N\cdot m; perpendicular distance (d) = 1.9000 m, determine the force (F) in N.
Given
Find
force (F), in N
Start with the thinking
- The governing relation printed in this handbook section is Moment of a force about a point.
- Everything except F is given, so isolate F symbolically first — never rearrange after the numbers are in.
- Tabulate each given with its unit and confirm the units are consistent with the relation before substituting.
- A force acting at a perpendicular distance d produces a moment.
Step-by-step solution
Step 1 — State the governing relation:
Step 2 — Rearrange symbolically for F:
Step 3
Step 4 — Substitute the given values:
Step 5 — Evaluate:
Step 6 — Check: returning F = 2,792 N to
reproduces the given quantities, and both sides carry the same units.
Why the other options are there
- 5,583 — kept a factor of two that cancels in the correct rearrangement.
- 1,396 — dropped that same factor in the other direction.
- 3,071 — rounded an intermediate value before the final step.
Reference: FE Handbook — Statics (Moments)
A statics problem uses Moment of a force. Given force (F) = 235.0 lb; moment (M) = 428.0 lb·ft, determine the moment arm (d) in ft.
Given
moment (M) = 428.0 lb·ft
Find
moment arm (d), in ft
Start with the thinking
- The governing relation printed in this handbook section is Moment of a force.
- Everything except d is given, so isolate d symbolically first — never rearrange after the numbers are in.
- Tabulate each given with its unit and confirm the units are consistent with the relation before substituting.
- Statics items reward recognising the unknown before touching a calculator.
Step-by-step solution
Step 1 — State the governing relation:
Step 2 — Rearrange the relation so that d stands alone on the left-hand side.
Step 3 — List the givens: force (F) = 235.0 lb, moment (M) = 428.0 lb·ft.
Step 4 — Substitute the given values into the rearranged relation.
Step 5 — Evaluate:
Step 6 — Check: returning d = 1.8213 ft to
reproduces the given quantities, and both sides carry the same units.
Why the other options are there
- 3.6426 — kept a factor of two that cancels in the correct rearrangement.
- 0.9106 — dropped that same factor in the other direction.
- 2.0034 — rounded an intermediate value before the final step.
Reference: FE Reference Handbook — Statics → Screw Thread
A statics problem uses Coulomb friction. Given friction coefficient (mu) = 0.3700; friction force (F) = 1,548 lb, determine the normal force (N) in lb.
Given
Find
normal force (N), in lb
Start with the thinking
- The governing relation printed in this handbook section is Coulomb friction.
- Everything except N is given, so isolate N symbolically first — never rearrange after the numbers are in.
- Tabulate each given with its unit and confirm the units are consistent with the relation before substituting.
- Statics items reward recognising the unknown before touching a calculator.
Step-by-step solution
Step 1 — State the governing relation:
Step 2 — Rearrange the relation so that N stands alone on the left-hand side.
Step 3
Step 4 — Substitute the given values into the rearranged relation.
Step 5 — Evaluate:
Step 6 — Check: returning N = 4,184 lb to
reproduces the given quantities, and both sides carry the same units.
Why the other options are there
- 8,368 — kept a factor of two that cancels in the correct rearrangement.
- 2,092 — dropped that same factor in the other direction.
- 4,602 — rounded an intermediate value before the final step.
Reference: FE Reference Handbook — Statics → Screw Thread
a cantilevered sign arm Given moment (M) = 6,275 N\cdot m; force (F) = 2,461 N, determine the perpendicular distance (d) in m.
Given
Find
perpendicular distance (d), in m
Start with the thinking
- The governing relation printed in this handbook section is Moment of a force about a point.
- Everything except d is given, so isolate d symbolically first — never rearrange after the numbers are in.
- Tabulate each given with its unit and confirm the units are consistent with the relation before substituting.
- A force acting at a perpendicular distance d produces a moment.
Step-by-step solution
Step 1 — State the governing relation:
Step 2 — Rearrange symbolically for d:
Step 3
Step 4 — Substitute the given values:
Step 5 — Evaluate:
Step 6 — Check: returning d = 2.5499 m to
reproduces the given quantities, and both sides carry the same units.
Why the other options are there
- 5.0998 — kept a factor of two that cancels in the correct rearrangement.
- 1.2749 — dropped that same factor in the other direction.
- 2.8049 — rounded an intermediate value before the final step.
Reference: FE Handbook — Statics (Moments)
A statics problem uses Moment of a force. Given force (F) = 423.0 lb; moment arm (d) = 1.6000 ft, determine the moment (M) in lb·ft.
Given
Find
moment (M), in lb·ft
Start with the thinking
- The governing relation printed in this handbook section is Moment of a force.
- Everything except M is given, so isolate M symbolically first — never rearrange after the numbers are in.
- Tabulate each given with its unit and confirm the units are consistent with the relation before substituting.
- Statics items reward recognising the unknown before touching a calculator.
Step-by-step solution
Step 1 — State the governing relation:
Step 2 — Rearrange the relation so that M stands alone on the left-hand side.
Step 3
Step 4 — Substitute the given values into the rearranged relation.
Step 5 — Evaluate:
Step 6 — Check: returning M = 676.8 lb·ft to
reproduces the given quantities, and both sides carry the same units.
Why the other options are there
- 1,354 — kept a factor of two that cancels in the correct rearrangement.
- 338.4 — dropped that same factor in the other direction.
- 744.5 — rounded an intermediate value before the final step.
Reference: FE Reference Handbook — Statics → Screw Thread