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Statics · FE Reference Handbook section

Statics
6 formulas
10 exam-style examples
~57 min
All Statics lectures

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.

Example 1
Moment of a force — solve for moment — Screw Thread

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

  • force(F)=1,271lbforce (F) = 1,271 lb
  • momentarm(d)=10.1000ftmoment arm (d) = 10.1000 ft

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

  1. Step 1 — State the governing relation:

    M=F×dM = F \times d
  2. Step 2 — Rearrange the relation so that M stands alone on the left-hand side.

  3. Step 3

    Listthegivens:force(F)=1,271lb,momentarm(d)=10.1000ftList the givens: force (F) = 1,271 lb, moment arm (d) = 10.1000 ft
  4. Step 4 — Substitute the given values into the rearranged relation.

  5. Step 5 — Evaluate:

    M=12837 lb⋅ftM = 12837\ \text{lb·ft}
  6. Step 6 — Check: returning M = 12,837 lb·ft to

    M=F×dM = F \times d

    reproduces the given quantities, and both sides carry the same units.

Answer:
M=12837 lb⋅ftM = 12837\ \text{lb·ft}

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

Example 2
Coulomb friction — solve for friction force — Screw Thread (2)

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

  • frictioncoefficient(mu)=0.6100friction coefficient (mu) = 0.6100
  • normalforce(N)=1,006lbnormal force (N) = 1,006 lb

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

  1. Step 1 — State the governing relation:

    F=μNF = \mu N
  2. Step 2 — Rearrange the relation so that F stands alone on the left-hand side.

  3. Step 3

    Listthegivens:frictioncoefficient(mu)=0.6100,normalforce(N)=1,006lbList the givens: friction coefficient (mu) = 0.6100, normal force (N) = 1,006 lb
  4. Step 4 — Substitute the given values into the rearranged relation.

  5. Step 5 — Evaluate:

    F=613.7 lbF = 613.7\ \text{lb}
  6. Step 6 — Check: returning F = 613.7 lb to

    F=μNF = \mu N

    reproduces the given quantities, and both sides carry the same units.

Answer:
F=613.7 lbF = 613.7\ \text{lb}

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

Example 3
Moment of a force about a point — solve for moment — Screw Thread (3)

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

  • force(F)=1,256Nforce (F) = 1,256 N
  • perpendiculardistance(d)=3.5000mperpendicular distance (d) = 3.5000 m

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

  1. Step 1 — State the governing relation:

    M=FdM = F d
  2. Step 2 — Rearrange symbolically for M:

    M=M=FdM = M = F d
  3. Step 3

    Listthegivens:force(F)=1,256N,perpendiculardistance(d)=3.5000mList the givens: force (F) = 1,256 N, perpendicular distance (d) = 3.5000 m
  4. Step 4 — Substitute the given values:

    M=M=12563.5000M = M = 1256 3.5000
  5. Step 5 — Evaluate:

    M=4394 N\cdotmM = 4394\ \text{N\cdot m}
  6. Step 6 — Check: returning M = 4,394 N\cdot m to

    M=FdM = F d

    reproduces the given quantities, and both sides carry the same units.

Answer:
M=4394 N\cdotmM = 4394\ \text{N\cdot m}

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)

Example 4
Moment of a force — solve for force — Screw Thread (4)

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

  • momentarm(d)=18.6000ftmoment arm (d) = 18.6000 ft
  • 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

  1. Step 1 — State the governing relation:

    M=F×dM = F \times d
  2. Step 2 — Rearrange the relation so that F stands alone on the left-hand side.

  3. Step 3 — List the givens: moment arm (d) = 18.6000 ft, moment (M) = 7,733 lb·ft.

  4. Step 4 — Substitute the given values into the rearranged relation.

  5. Step 5 — Evaluate:

    F=415.8 lbF = 415.8\ \text{lb}
  6. Step 6 — Check: returning F = 415.8 lb to

    M=F×dM = F \times d

    reproduces the given quantities, and both sides carry the same units.

Answer:
F=415.8 lbF = 415.8\ \text{lb}

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

Example 5
Coulomb friction — solve for friction coefficient — Screw Thread (5)

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

  • normalforce(N)=1,131lbnormal force (N) = 1,131 lb
  • frictionforce(F)=196.0lbfriction force (F) = 196.0 lb

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

  1. Step 1 — State the governing relation:

    F=μNF = \mu N
  2. Step 2 — Rearrange the relation so that mu stands alone on the left-hand side.

  3. Step 3

    Listthegivens:normalforce(N)=1,131lb,frictionforce(F)=196.0lbList the givens: normal force (N) = 1,131 lb, friction force (F) = 196.0 lb
  4. Step 4 — Substitute the given values into the rearranged relation.

  5. Step 5 — Evaluate:

    μ=0.1733\mu = 0.1733
  6. Step 6 — Check: returning mu = 0.1733 to

    F=μNF = \mu N

    reproduces the given quantities, and both sides carry the same units.

Answer:
μ=0.1733\mu = 0.1733

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

Example 6
Moment of a force about a point — solve for force — Screw Thread (6)

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

  • moment(M)=5,304N⋅mmoment (M) = 5,304 N\cdot m
  • perpendiculardistance(d)=1.9000mperpendicular distance (d) = 1.9000 m

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

  1. Step 1 — State the governing relation:

    M=FdM = F d
  2. Step 2 — Rearrange symbolically for F:

    F=F=MdF = F = \dfrac{M}{d}
  3. Step 3

    Listthegivens:moment(M)=5,304N⋅m,perpendiculardistance(d)=1.9000mList the givens: moment (M) = 5,304 N\cdot m, perpendicular distance (d) = 1.9000 m
  4. Step 4 — Substitute the given values:

    F=F=53041.9000F = F = \dfrac{5304}{1.9000}
  5. Step 5 — Evaluate:

    F=2792 NF = 2792\ \text{N}
  6. Step 6 — Check: returning F = 2,792 N to

    M=FdM = F d

    reproduces the given quantities, and both sides carry the same units.

Answer:
F=2792 NF = 2792\ \text{N}

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)

Example 7
Moment of a force — solve for moment arm — Screw Thread (7)

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

  • force(F)=235.0lbforce (F) = 235.0 lb
  • 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

  1. Step 1 — State the governing relation:

    M=F×dM = F \times d
  2. Step 2 — Rearrange the relation so that d stands alone on the left-hand side.

  3. Step 3 — List the givens: force (F) = 235.0 lb, moment (M) = 428.0 lb·ft.

  4. Step 4 — Substitute the given values into the rearranged relation.

  5. Step 5 — Evaluate:

    d=1.8213 ftd = 1.8213\ \text{ft}
  6. Step 6 — Check: returning d = 1.8213 ft to

    M=F×dM = F \times d

    reproduces the given quantities, and both sides carry the same units.

Answer:
d=1.8213 ftd = 1.8213\ \text{ft}

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

Example 8
Coulomb friction — solve for normal force — Screw Thread (8)

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

  • frictioncoefficient(mu)=0.3700friction coefficient (mu) = 0.3700
  • frictionforce(F)=1,548lbfriction force (F) = 1,548 lb

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

  1. Step 1 — State the governing relation:

    F=μNF = \mu N
  2. Step 2 — Rearrange the relation so that N stands alone on the left-hand side.

  3. Step 3

    Listthegivens:frictioncoefficient(mu)=0.3700,frictionforce(F)=1,548lbList the givens: friction coefficient (mu) = 0.3700, friction force (F) = 1,548 lb
  4. Step 4 — Substitute the given values into the rearranged relation.

  5. Step 5 — Evaluate:

    N=4184 lbN = 4184\ \text{lb}
  6. Step 6 — Check: returning N = 4,184 lb to

    F=μNF = \mu N

    reproduces the given quantities, and both sides carry the same units.

Answer:
N=4184 lbN = 4184\ \text{lb}

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

Example 9
Moment of a force about a point — solve for perpendicular distance — Screw Thread (9)

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

  • moment(M)=6,275N⋅mmoment (M) = 6,275 N\cdot m
  • force(F)=2,461Nforce (F) = 2,461 N

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

  1. Step 1 — State the governing relation:

    M=FdM = F d
  2. Step 2 — Rearrange symbolically for d:

    d=d=MFd = d = \dfrac{M}{F}
  3. Step 3

    Listthegivens:moment(M)=6,275N⋅m,force(F)=2,461NList the givens: moment (M) = 6,275 N\cdot m, force (F) = 2,461 N
  4. Step 4 — Substitute the given values:

    d=d=62752461d = d = \dfrac{6275}{2461}
  5. Step 5 — Evaluate:

    d=2.5499 md = 2.5499\ \text{m}
  6. Step 6 — Check: returning d = 2.5499 m to

    M=FdM = F d

    reproduces the given quantities, and both sides carry the same units.

Answer:
d=2.5499 md = 2.5499\ \text{m}

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)

Example 10
Moment of a force — solve for moment (case 2) — Screw Thread (10)

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

  • force(F)=423.0lbforce (F) = 423.0 lb
  • momentarm(d)=1.6000ftmoment arm (d) = 1.6000 ft

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

  1. Step 1 — State the governing relation:

    M=F×dM = F \times d
  2. Step 2 — Rearrange the relation so that M stands alone on the left-hand side.

  3. Step 3

    Listthegivens:force(F)=423.0lb,momentarm(d)=1.6000ftList the givens: force (F) = 423.0 lb, moment arm (d) = 1.6000 ft
  4. Step 4 — Substitute the given values into the rearranged relation.

  5. Step 5 — Evaluate:

    M=676.8 lb⋅ftM = 676.8\ \text{lb·ft}
  6. Step 6 — Check: returning M = 676.8 lb·ft to

    M=F×dM = F \times d

    reproduces the given quantities, and both sides carry the same units.

Answer:
M=676.8 lb⋅ftM = 676.8\ \text{lb·ft}

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

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