Skip to content

Thermal Deformations

Mechanics of Materials · FE Reference Handbook section

Mechanics of Materials
6 formulas
10 exam-style examples
~57 min
All Mechanics of Materials 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
Axial elongation — solve for elongation — Thermal Deformations

A mechanics of materials problem uses Axial elongation. Given axial load (P) = 85.0000 kip; length (L) = 108.0 in; area (A) = 4.1000 in²; modulus (E) = 29,000 ksi, determine the elongation (delta) in in.

Given

  • axialload(P)=85.0000kipaxial load (P) = 85.0000 kip
  • length(L)=108.0inlength (L) = 108.0 in
  • area(A)=4.1000in2area (A) = 4.1000 in^{2}
  • modulus(E)=29,000ksimodulus (E) = 29,000 ksi

Find

elongation (delta), in in

Start with the thinking

  • The governing relation printed in this handbook section is Axial elongation.
  • Everything except delta is given, so isolate delta 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.
  • Mechanics of Materials items reward recognising the unknown before touching a calculator.

Step-by-step solution

  1. Step 1 — State the governing relation:

    δ=PL/(AE)\delta = P L / (A E)
  2. Step 2 — Rearrange the relation so that delta stands alone on the left-hand side.

  3. Step 3 — List the givens: axial load (P) = 85.0000 kip, length (L) = 108.0 in, area (A) = 4.1000 in², modulus (E) = 29,000 ksi.

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

  5. Step 5 — Evaluate:

    δ=0.0772 in\delta = 0.0772\ \text{in}
  6. Step 6 — Check: returning delta = 0.0772 in to

    δ=PL/(AE)\delta = P L / (A E)

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

Answer:
δ=0.0772 in\delta = 0.0772\ \text{in}

Why the other options are there

  • 0.1544 — kept a factor of two that cancels in the correct rearrangement.
  • 0.0386 — dropped that same factor in the other direction.
  • 0.0849 — rounded an intermediate value before the final step.

Reference: FE Reference Handbook — Mechanics of Materials → Thermal Deformations

Example 2
Axial elongation — solve for axial load — Thermal Deformations (2)

A mechanics of materials problem uses Axial elongation. Given length (L) = 129.0 in; area (A) = 5.9000 in²; modulus (E) = 17,000 ksi; elongation (delta) = 0.9995 in, determine the axial load (P) in kip.

Given

  • length(L)=129.0inlength (L) = 129.0 in
  • area(A)=5.9000in2area (A) = 5.9000 in^{2}
  • modulus(E)=17,000ksimodulus (E) = 17,000 ksi
  • elongation(delta)=0.9995inelongation (delta) = 0.9995 in

Find

axial load (P), in kip

Start with the thinking

  • The governing relation printed in this handbook section is Axial elongation.
  • Everything except P is given, so isolate P 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.
  • Mechanics of Materials items reward recognising the unknown before touching a calculator.

Step-by-step solution

  1. Step 1 — State the governing relation:

    δ=PL/(AE)\delta = P L / (A E)
  2. Step 2 — Rearrange the relation so that P stands alone on the left-hand side.

  3. Step 3 — List the givens: length (L) = 129.0 in, area (A) = 5.9000 in², modulus (E) = 17,000 ksi, elongation (delta) = 0.9995 in.

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

  5. Step 5 — Evaluate:

    P=777.1 kipP = 777.1\ \text{kip}
  6. Step 6 — Check: returning P = 777.1 kip to

    δ=PL/(AE)\delta = P L / (A E)

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

Answer:
P=777.1 kipP = 777.1\ \text{kip}

Why the other options are there

  • 1,554 — kept a factor of two that cancels in the correct rearrangement.
  • 388.6 — dropped that same factor in the other direction.
  • 854.8 — rounded an intermediate value before the final step.

Reference: FE Reference Handbook — Mechanics of Materials → Thermal Deformations

Example 3
Axial elongation — solve for area — Thermal Deformations (3)

A mechanics of materials problem uses Axial elongation. Given axial load (P) = 37.0000 kip; length (L) = 99.0000 in; modulus (E) = 26,000 ksi; elongation (delta) = 0.1275 in, determine the area (A) in in².

Given

  • axialload(P)=37.0000kipaxial load (P) = 37.0000 kip
  • length(L)=99.0000inlength (L) = 99.0000 in
  • modulus(E)=26,000ksimodulus (E) = 26,000 ksi
  • elongation(delta)=0.1275inelongation (delta) = 0.1275 in

Find

area (A), in in²

Start with the thinking

  • The governing relation printed in this handbook section is Axial elongation.
  • Everything except A is given, so isolate A 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.
  • Mechanics of Materials items reward recognising the unknown before touching a calculator.

Step-by-step solution

  1. Step 1 — State the governing relation:

    δ=PL/(AE)\delta = P L / (A E)
  2. Step 2 — Rearrange the relation so that A stands alone on the left-hand side.

  3. Step 3 — List the givens: axial load (P) = 37.0000 kip, length (L) = 99.0000 in, modulus (E) = 26,000 ksi, elongation (delta) = 0.1275 in.

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

  5. Step 5 — Evaluate:

    A=1.1050 in²A = 1.1050\ \text{in²}
  6. Step 6 — Check: returning A = 1.1050 in² to

    δ=PL/(AE)\delta = P L / (A E)

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

Answer:
A=1.1050 in²A = 1.1050\ \text{in²}

Why the other options are there

  • 2.2100 — kept a factor of two that cancels in the correct rearrangement.
  • 0.5525 — dropped that same factor in the other direction.
  • 1.2155 — rounded an intermediate value before the final step.

Reference: FE Reference Handbook — Mechanics of Materials → Thermal Deformations

Example 4
Axial elongation — solve for length — Thermal Deformations (4)

A mechanics of materials problem uses Axial elongation. Given axial load (P) = 26.0000 kip; area (A) = 2.1000 in²; modulus (E) = 20,000 ksi; elongation (delta) = 0.5204 in, determine the length (L) in in.

Given

  • axialload(P)=26.0000kipaxial load (P) = 26.0000 kip
  • area(A)=2.1000in2area (A) = 2.1000 in^{2}
  • modulus(E)=20,000ksimodulus (E) = 20,000 ksi
  • elongation(delta)=0.5204inelongation (delta) = 0.5204 in

Find

length (L), in in

Start with the thinking

  • The governing relation printed in this handbook section is Axial elongation.
  • Everything except L is given, so isolate L 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.
  • Mechanics of Materials items reward recognising the unknown before touching a calculator.

Step-by-step solution

  1. Step 1 — State the governing relation:

    δ=PL/(AE)\delta = P L / (A E)
  2. Step 2 — Rearrange the relation so that L stands alone on the left-hand side.

  3. Step 3 — List the givens: axial load (P) = 26.0000 kip, area (A) = 2.1000 in², modulus (E) = 20,000 ksi, elongation (delta) = 0.5204 in.

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

  5. Step 5 — Evaluate:

    L=840.6 inL = 840.6\ \text{in}
  6. Step 6 — Check: returning L = 840.6 in to

    δ=PL/(AE)\delta = P L / (A E)

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

Answer:
L=840.6 inL = 840.6\ \text{in}

Why the other options are there

  • 1,681 — kept a factor of two that cancels in the correct rearrangement.
  • 420.3 — dropped that same factor in the other direction.
  • 924.7 — rounded an intermediate value before the final step.

Reference: FE Reference Handbook — Mechanics of Materials → Thermal Deformations

Example 5
Axial elongation — solve for elongation (case 2) — Thermal Deformations (5)

A mechanics of materials problem uses Axial elongation. Given axial load (P) = 80.0000 kip; length (L) = 191.0 in; area (A) = 7.2000 in²; modulus (E) = 27,000 ksi, determine the elongation (delta) in in.

Given

  • axialload(P)=80.0000kipaxial load (P) = 80.0000 kip
  • length(L)=191.0inlength (L) = 191.0 in
  • area(A)=7.2000in2area (A) = 7.2000 in^{2}
  • modulus(E)=27,000ksimodulus (E) = 27,000 ksi

Find

elongation (delta), in in

Start with the thinking

  • The governing relation printed in this handbook section is Axial elongation.
  • Everything except delta is given, so isolate delta 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.
  • Mechanics of Materials items reward recognising the unknown before touching a calculator.

Step-by-step solution

  1. Step 1 — State the governing relation:

    δ=PL/(AE)\delta = P L / (A E)
  2. Step 2 — Rearrange the relation so that delta stands alone on the left-hand side.

  3. Step 3 — List the givens: axial load (P) = 80.0000 kip, length (L) = 191.0 in, area (A) = 7.2000 in², modulus (E) = 27,000 ksi.

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

  5. Step 5 — Evaluate:

    δ=0.0786 in\delta = 0.0786\ \text{in}
  6. Step 6 — Check: returning delta = 0.0786 in to

    δ=PL/(AE)\delta = P L / (A E)

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

Answer:
δ=0.0786 in\delta = 0.0786\ \text{in}

Why the other options are there

  • 0.1572 — kept a factor of two that cancels in the correct rearrangement.
  • 0.0393 — dropped that same factor in the other direction.
  • 0.0865 — rounded an intermediate value before the final step.

Reference: FE Reference Handbook — Mechanics of Materials → Thermal Deformations

Example 6
Axial elongation — solve for axial load (case 2) — Thermal Deformations (6)

A mechanics of materials problem uses Axial elongation. Given length (L) = 181.0 in; area (A) = 6.9000 in²; modulus (E) = 27,000 ksi; elongation (delta) = 0.2371 in, determine the axial load (P) in kip.

Given

  • length(L)=181.0inlength (L) = 181.0 in
  • area(A)=6.9000in2area (A) = 6.9000 in^{2}
  • modulus(E)=27,000ksimodulus (E) = 27,000 ksi
  • elongation(delta)=0.2371inelongation (delta) = 0.2371 in

Find

axial load (P), in kip

Start with the thinking

  • The governing relation printed in this handbook section is Axial elongation.
  • Everything except P is given, so isolate P 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.
  • Mechanics of Materials items reward recognising the unknown before touching a calculator.

Step-by-step solution

  1. Step 1 — State the governing relation:

    δ=PL/(AE)\delta = P L / (A E)
  2. Step 2 — Rearrange the relation so that P stands alone on the left-hand side.

  3. Step 3 — List the givens: length (L) = 181.0 in, area (A) = 6.9000 in², modulus (E) = 27,000 ksi, elongation (delta) = 0.2371 in.

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

  5. Step 5 — Evaluate:

    P=244.0 kipP = 244.0\ \text{kip}
  6. Step 6 — Check: returning P = 244.0 kip to

    δ=PL/(AE)\delta = P L / (A E)

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

Answer:
P=244.0 kipP = 244.0\ \text{kip}

Why the other options are there

  • 488.1 — kept a factor of two that cancels in the correct rearrangement.
  • 122.0 — dropped that same factor in the other direction.
  • 268.4 — rounded an intermediate value before the final step.

Reference: FE Reference Handbook — Mechanics of Materials → Thermal Deformations

Example 7
Axial elongation — solve for area (case 2) — Thermal Deformations (7)

A mechanics of materials problem uses Axial elongation. Given axial load (P) = 51.0000 kip; length (L) = 82.0000 in; modulus (E) = 10,000 ksi; elongation (delta) = 0.2376 in, determine the area (A) in in².

Given

  • axialload(P)=51.0000kipaxial load (P) = 51.0000 kip
  • length(L)=82.0000inlength (L) = 82.0000 in
  • modulus(E)=10,000ksimodulus (E) = 10,000 ksi
  • elongation(delta)=0.2376inelongation (delta) = 0.2376 in

Find

area (A), in in²

Start with the thinking

  • The governing relation printed in this handbook section is Axial elongation.
  • Everything except A is given, so isolate A 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.
  • Mechanics of Materials items reward recognising the unknown before touching a calculator.

Step-by-step solution

  1. Step 1 — State the governing relation:

    δ=PL/(AE)\delta = P L / (A E)
  2. Step 2 — Rearrange the relation so that A stands alone on the left-hand side.

  3. Step 3 — List the givens: axial load (P) = 51.0000 kip, length (L) = 82.0000 in, modulus (E) = 10,000 ksi, elongation (delta) = 0.2376 in.

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

  5. Step 5 — Evaluate:

    A=1.7601 in²A = 1.7601\ \text{in²}
  6. Step 6 — Check: returning A = 1.7601 in² to

    δ=PL/(AE)\delta = P L / (A E)

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

Answer:
A=1.7601 in²A = 1.7601\ \text{in²}

Why the other options are there

  • 3.5202 — kept a factor of two that cancels in the correct rearrangement.
  • 0.8801 — dropped that same factor in the other direction.
  • 1.9361 — rounded an intermediate value before the final step.

Reference: FE Reference Handbook — Mechanics of Materials → Thermal Deformations

Example 8
Axial elongation — solve for length (case 2) — Thermal Deformations (8)

A mechanics of materials problem uses Axial elongation. Given axial load (P) = 46.0000 kip; area (A) = 3.8000 in²; modulus (E) = 21,000 ksi; elongation (delta) = 0.0527 in, determine the length (L) in in.

Given

  • axialload(P)=46.0000kipaxial load (P) = 46.0000 kip
  • area(A)=3.8000in2area (A) = 3.8000 in^{2}
  • modulus(E)=21,000ksimodulus (E) = 21,000 ksi
  • elongation(delta)=0.0527inelongation (delta) = 0.0527 in

Find

length (L), in in

Start with the thinking

  • The governing relation printed in this handbook section is Axial elongation.
  • Everything except L is given, so isolate L 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.
  • Mechanics of Materials items reward recognising the unknown before touching a calculator.

Step-by-step solution

  1. Step 1 — State the governing relation:

    δ=PL/(AE)\delta = P L / (A E)
  2. Step 2 — Rearrange the relation so that L stands alone on the left-hand side.

  3. Step 3 — List the givens: axial load (P) = 46.0000 kip, area (A) = 3.8000 in², modulus (E) = 21,000 ksi, elongation (delta) = 0.0527 in.

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

  5. Step 5 — Evaluate:

    L=91.4230 inL = 91.4230\ \text{in}
  6. Step 6 — Check: returning L = 91.4230 in to

    δ=PL/(AE)\delta = P L / (A E)

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

Answer:
L=91.4230 inL = 91.4230\ \text{in}

Why the other options are there

  • 182.8 — kept a factor of two that cancels in the correct rearrangement.
  • 45.7115 — dropped that same factor in the other direction.
  • 100.6 — rounded an intermediate value before the final step.

Reference: FE Reference Handbook — Mechanics of Materials → Thermal Deformations

Example 9
Axial elongation — solve for elongation (case 3) — Thermal Deformations (9)

A mechanics of materials problem uses Axial elongation. Given axial load (P) = 95.0000 kip; length (L) = 224.0 in; area (A) = 9.3000 in²; modulus (E) = 21,000 ksi, determine the elongation (delta) in in.

Given

  • axialload(P)=95.0000kipaxial load (P) = 95.0000 kip
  • length(L)=224.0inlength (L) = 224.0 in
  • area(A)=9.3000in2area (A) = 9.3000 in^{2}
  • modulus(E)=21,000ksimodulus (E) = 21,000 ksi

Find

elongation (delta), in in

Start with the thinking

  • The governing relation printed in this handbook section is Axial elongation.
  • Everything except delta is given, so isolate delta 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.
  • Mechanics of Materials items reward recognising the unknown before touching a calculator.

Step-by-step solution

  1. Step 1 — State the governing relation:

    δ=PL/(AE)\delta = P L / (A E)
  2. Step 2 — Rearrange the relation so that delta stands alone on the left-hand side.

  3. Step 3 — List the givens: axial load (P) = 95.0000 kip, length (L) = 224.0 in, area (A) = 9.3000 in², modulus (E) = 21,000 ksi.

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

  5. Step 5 — Evaluate:

    δ=0.1090 in\delta = 0.1090\ \text{in}
  6. Step 6 — Check: returning delta = 0.1090 in to

    δ=PL/(AE)\delta = P L / (A E)

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

Answer:
δ=0.1090 in\delta = 0.1090\ \text{in}

Why the other options are there

  • 0.2179 — kept a factor of two that cancels in the correct rearrangement.
  • 0.0545 — dropped that same factor in the other direction.
  • 0.1199 — rounded an intermediate value before the final step.

Reference: FE Reference Handbook — Mechanics of Materials → Thermal Deformations

Example 10
Axial elongation — solve for axial load (case 3) — Thermal Deformations (10)

A mechanics of materials problem uses Axial elongation. Given length (L) = 34.0000 in; area (A) = 8.2000 in²; modulus (E) = 13,000 ksi; elongation (delta) = 0.7367 in, determine the axial load (P) in kip.

Given

  • length(L)=34.0000inlength (L) = 34.0000 in
  • area(A)=8.2000in2area (A) = 8.2000 in^{2}
  • modulus(E)=13,000ksimodulus (E) = 13,000 ksi
  • elongation(delta)=0.7367inelongation (delta) = 0.7367 in

Find

axial load (P), in kip

Start with the thinking

  • The governing relation printed in this handbook section is Axial elongation.
  • Everything except P is given, so isolate P 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.
  • Mechanics of Materials items reward recognising the unknown before touching a calculator.

Step-by-step solution

  1. Step 1 — State the governing relation:

    δ=PL/(AE)\delta = P L / (A E)
  2. Step 2 — Rearrange the relation so that P stands alone on the left-hand side.

  3. Step 3 — List the givens: length (L) = 34.0000 in, area (A) = 8.2000 in², modulus (E) = 13,000 ksi, elongation (delta) = 0.7367 in.

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

  5. Step 5 — Evaluate:

    P=2310 kipP = 2310\ \text{kip}
  6. Step 6 — Check: returning P = 2,310 kip to

    δ=PL/(AE)\delta = P L / (A E)

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

Answer:
P=2310 kipP = 2310\ \text{kip}

Why the other options are there

  • 4,620 — kept a factor of two that cancels in the correct rearrangement.
  • 1,155 — dropped that same factor in the other direction.
  • 2,541 — rounded an intermediate value before the final step.

Reference: FE Reference Handbook — Mechanics of Materials → Thermal Deformations

© 2026 Dr. Steve Efe. Civil Engineering Capstone Studio. All rights reserved.