Skip to content

Concept of Weight

Dynamics · FE Reference Handbook section

Dynamics
4 formulas
10 exam-style examples
~53 min
All Dynamics 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
Constant-acceleration kinematics — solve for final velocity — Concept of Weight

A dynamics problem uses Constant-acceleration kinematics. Given initial velocity (v0) = 53.0000 ft/s; acceleration (a) = -16.5000 ft/s²; distance (s) = 306.0 ft, determine the final velocity (v) in ft/s.

Given

  • initialvelocity(v0)=53.0000ft/sinitial velocity (v_{0}) = 53.0000 ft/s
  • acceleration(a)=−16.5000ft/s2acceleration (a) = -16.5000 ft/s^{2}
  • distance(s)=306.0ftdistance (s) = 306.0 ft

Find

final velocity (v), in ft/s

Start with the thinking

  • The governing relation printed in this handbook section is Constant-acceleration kinematics.
  • Everything except v is given, so isolate v 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.
  • Dynamics items reward recognising the unknown before touching a calculator.

Step-by-step solution

  1. Step 1 — State the governing relation:

    v2=v02+2asv^2 = v_0^2 + 2 a s
  2. Step 2 — Rearrange the relation so that v stands alone on the left-hand side.

  3. Step 3 — List the givens: initial velocity (v0) = 53.0000 ft/s, acceleration (a) = -16.5000 ft/s², distance (s) = 306.0 ft.

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

  5. Step 5 — Evaluate:

    v=0.0000 ft/sv = 0.0000\ \text{ft/s}
  6. Step 6 — Check: returning v = 0.0000 ft/s to

    v2=v02+2asv^2 = v_0^2 + 2 a s

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

Answer:
v=0.0000 ft/sv = 0.0000\ \text{ft/s}

Why the other options are there

  • 0.0000 — kept a factor of two that cancels in the correct rearrangement.
  • 0.0000 — dropped that same factor in the other direction.
  • 0.0000 — rounded an intermediate value before the final step.

Reference: FE Reference Handbook — Dynamics → Concept of Weight

Example 2
Constant-acceleration kinematics — solve for acceleration — Concept of Weight (2)

A dynamics problem uses Constant-acceleration kinematics. Given initial velocity (v0) = 98.0000 ft/s; distance (s) = 398.0 ft; final velocity (v) = 119.2 ft/s, determine the acceleration (a) in ft/s².

Given

  • initialvelocity(v0)=98.0000ft/sinitial velocity (v_{0}) = 98.0000 ft/s
  • distance(s)=398.0ftdistance (s) = 398.0 ft
  • finalvelocity(v)=119.2ft/sfinal velocity (v) = 119.2 ft/s

Find

acceleration (a), in ft/s²

Start with the thinking

  • The governing relation printed in this handbook section is Constant-acceleration kinematics.
  • 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.
  • Dynamics items reward recognising the unknown before touching a calculator.

Step-by-step solution

  1. Step 1 — State the governing relation:

    v2=v02+2asv^2 = v_0^2 + 2 a s
  2. Step 2 — Rearrange the relation so that a stands alone on the left-hand side.

  3. Step 3 — List the givens: initial velocity (v0) = 98.0000 ft/s, distance (s) = 398.0 ft, final velocity (v) = 119.2 ft/s.

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

  5. Step 5 — Evaluate:

    a=5.7847 ft/s²a = 5.7847\ \text{ft/s²}
  6. Step 6 — Check: returning a = 5.7847 ft/s² to

    v2=v02+2asv^2 = v_0^2 + 2 a s

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

Answer:
a=5.7847 ft/s²a = 5.7847\ \text{ft/s²}

Why the other options are there

  • 11.5694 — kept a factor of two that cancels in the correct rearrangement.
  • 2.8924 — dropped that same factor in the other direction.
  • 6.3632 — rounded an intermediate value before the final step.

Reference: FE Reference Handbook — Dynamics → Concept of Weight

Example 3
Constant-acceleration kinematics — solve for distance — Concept of Weight (3)

A dynamics problem uses Constant-acceleration kinematics. Given initial velocity (v0) = 37.0000 ft/s; acceleration (a) = 16.5000 ft/s²; final velocity (v) = 101.2 ft/s, determine the distance (s) in ft.

Given

  • initialvelocity(v0)=37.0000ft/sinitial velocity (v_{0}) = 37.0000 ft/s
  • acceleration(a)=16.5000ft/s2acceleration (a) = 16.5000 ft/s^{2}
  • finalvelocity(v)=101.2ft/sfinal velocity (v) = 101.2 ft/s

Find

distance (s), in ft

Start with the thinking

  • The governing relation printed in this handbook section is Constant-acceleration kinematics.
  • Everything except s is given, so isolate s 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.
  • Dynamics items reward recognising the unknown before touching a calculator.

Step-by-step solution

  1. Step 1 — State the governing relation:

    v2=v02+2asv^2 = v_0^2 + 2 a s
  2. Step 2 — Rearrange the relation so that s stands alone on the left-hand side.

  3. Step 3 — List the givens: initial velocity (v0) = 37.0000 ft/s, acceleration (a) = 16.5000 ft/s², final velocity (v) = 101.2 ft/s.

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

  5. Step 5 — Evaluate:

    s=268.9 fts = 268.9\ \text{ft}
  6. Step 6 — Check: returning s = 268.9 ft to

    v2=v02+2asv^2 = v_0^2 + 2 a s

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

Answer:
s=268.9 fts = 268.9\ \text{ft}

Why the other options are there

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

Reference: FE Reference Handbook — Dynamics → Concept of Weight

Example 4
Constant-acceleration kinematics — solve for final velocity (case 2) — Concept of Weight (4)

A dynamics problem uses Constant-acceleration kinematics. Given initial velocity (v0) = 77.0000 ft/s; acceleration (a) = -1.0000 ft/s²; distance (s) = 73.0000 ft, determine the final velocity (v) in ft/s.

Given

  • initialvelocity(v0)=77.0000ft/sinitial velocity (v_{0}) = 77.0000 ft/s
  • acceleration(a)=−1.0000ft/s2acceleration (a) = -1.0000 ft/s^{2}
  • distance(s)=73.0000ftdistance (s) = 73.0000 ft

Find

final velocity (v), in ft/s

Start with the thinking

  • The governing relation printed in this handbook section is Constant-acceleration kinematics.
  • Everything except v is given, so isolate v 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.
  • Dynamics items reward recognising the unknown before touching a calculator.

Step-by-step solution

  1. Step 1 — State the governing relation:

    v2=v02+2asv^2 = v_0^2 + 2 a s
  2. Step 2 — Rearrange the relation so that v stands alone on the left-hand side.

  3. Step 3 — List the givens: initial velocity (v0) = 77.0000 ft/s, acceleration (a) = -1.0000 ft/s², distance (s) = 73.0000 ft.

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

  5. Step 5 — Evaluate:

    v=76.0460 ft/sv = 76.0460\ \text{ft/s}
  6. Step 6 — Check: returning v = 76.0460 ft/s to

    v2=v02+2asv^2 = v_0^2 + 2 a s

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

Answer:
v=76.0460 ft/sv = 76.0460\ \text{ft/s}

Why the other options are there

  • 152.1 — kept a factor of two that cancels in the correct rearrangement.
  • 38.0230 — dropped that same factor in the other direction.
  • 83.6506 — rounded an intermediate value before the final step.

Reference: FE Reference Handbook — Dynamics → Concept of Weight

Example 5
Constant-acceleration kinematics — solve for acceleration (case 2) — Concept of Weight (5)

A dynamics problem uses Constant-acceleration kinematics. Given initial velocity (v0) = 39.0000 ft/s; distance (s) = 158.0 ft; final velocity (v) = 79.8000 ft/s, determine the acceleration (a) in ft/s².

Given

  • initialvelocity(v0)=39.0000ft/sinitial velocity (v_{0}) = 39.0000 ft/s
  • distance(s)=158.0ftdistance (s) = 158.0 ft
  • finalvelocity(v)=79.8000ft/sfinal velocity (v) = 79.8000 ft/s

Find

acceleration (a), in ft/s²

Start with the thinking

  • The governing relation printed in this handbook section is Constant-acceleration kinematics.
  • 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.
  • Dynamics items reward recognising the unknown before touching a calculator.

Step-by-step solution

  1. Step 1 — State the governing relation:

    v2=v02+2asv^2 = v_0^2 + 2 a s
  2. Step 2 — Rearrange the relation so that a stands alone on the left-hand side.

  3. Step 3 — List the givens: initial velocity (v0) = 39.0000 ft/s, distance (s) = 158.0 ft, final velocity (v) = 79.8000 ft/s.

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

  5. Step 5 — Evaluate:

    a=15.3387 ft/s²a = 15.3387\ \text{ft/s²}
  6. Step 6 — Check: returning a = 15.3387 ft/s² to

    v2=v02+2asv^2 = v_0^2 + 2 a s

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

Answer:
a=15.3387 ft/s²a = 15.3387\ \text{ft/s²}

Why the other options are there

  • 30.6775 — kept a factor of two that cancels in the correct rearrangement.
  • 7.6694 — dropped that same factor in the other direction.
  • 16.8726 — rounded an intermediate value before the final step.

Reference: FE Reference Handbook — Dynamics → Concept of Weight

Example 6
Constant-acceleration kinematics — solve for distance (case 2) — Concept of Weight (6)

A dynamics problem uses Constant-acceleration kinematics. Given initial velocity (v0) = 94.0000 ft/s; acceleration (a) = -2.5000 ft/s²; final velocity (v) = 13.8000 ft/s, determine the distance (s) in ft.

Given

  • initialvelocity(v0)=94.0000ft/sinitial velocity (v_{0}) = 94.0000 ft/s
  • acceleration(a)=−2.5000ft/s2acceleration (a) = -2.5000 ft/s^{2}
  • finalvelocity(v)=13.8000ft/sfinal velocity (v) = 13.8000 ft/s

Find

distance (s), in ft

Start with the thinking

  • The governing relation printed in this handbook section is Constant-acceleration kinematics.
  • Everything except s is given, so isolate s 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.
  • Dynamics items reward recognising the unknown before touching a calculator.

Step-by-step solution

  1. Step 1 — State the governing relation:

    v2=v02+2asv^2 = v_0^2 + 2 a s
  2. Step 2 — Rearrange the relation so that s stands alone on the left-hand side.

  3. Step 3 — List the givens: initial velocity (v0) = 94.0000 ft/s, acceleration (a) = -2.5000 ft/s², final velocity (v) = 13.8000 ft/s.

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

  5. Step 5 — Evaluate:

    s=1729 fts = 1729\ \text{ft}
  6. Step 6 — Check: returning s = 1,729 ft to

    v2=v02+2asv^2 = v_0^2 + 2 a s

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

Answer:
s=1729 fts = 1729\ \text{ft}

Why the other options are there

  • 3,458 — kept a factor of two that cancels in the correct rearrangement.
  • 864.6 — dropped that same factor in the other direction.
  • 1,902 — rounded an intermediate value before the final step.

Reference: FE Reference Handbook — Dynamics → Concept of Weight

Example 7
Constant-acceleration kinematics — solve for final velocity (case 3) — Concept of Weight (7)

A dynamics problem uses Constant-acceleration kinematics. Given initial velocity (v0) = 96.0000 ft/s; acceleration (a) = 21.0000 ft/s²; distance (s) = 90.0000 ft, determine the final velocity (v) in ft/s.

Given

  • initialvelocity(v0)=96.0000ft/sinitial velocity (v_{0}) = 96.0000 ft/s
  • acceleration(a)=21.0000ft/s2acceleration (a) = 21.0000 ft/s^{2}
  • distance(s)=90.0000ftdistance (s) = 90.0000 ft

Find

final velocity (v), in ft/s

Start with the thinking

  • The governing relation printed in this handbook section is Constant-acceleration kinematics.
  • Everything except v is given, so isolate v 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.
  • Dynamics items reward recognising the unknown before touching a calculator.

Step-by-step solution

  1. Step 1 — State the governing relation:

    v2=v02+2asv^2 = v_0^2 + 2 a s
  2. Step 2 — Rearrange the relation so that v stands alone on the left-hand side.

  3. Step 3 — List the givens: initial velocity (v0) = 96.0000 ft/s, acceleration (a) = 21.0000 ft/s², distance (s) = 90.0000 ft.

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

  5. Step 5 — Evaluate:

    v=114.0 ft/sv = 114.0\ \text{ft/s}
  6. Step 6 — Check: returning v = 114.0 ft/s to

    v2=v02+2asv^2 = v_0^2 + 2 a s

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

Answer:
v=114.0 ft/sv = 114.0\ \text{ft/s}

Why the other options are there

  • 228.0 — kept a factor of two that cancels in the correct rearrangement.
  • 57.0000 — dropped that same factor in the other direction.
  • 125.4 — rounded an intermediate value before the final step.

Reference: FE Reference Handbook — Dynamics → Concept of Weight

Example 8
Constant-acceleration kinematics — solve for acceleration (case 3) — Concept of Weight (8)

A dynamics problem uses Constant-acceleration kinematics. Given initial velocity (v0) = 54.0000 ft/s; distance (s) = 166.0 ft; final velocity (v) = 18.9000 ft/s, determine the acceleration (a) in ft/s².

Given

  • initialvelocity(v0)=54.0000ft/sinitial velocity (v_{0}) = 54.0000 ft/s
  • distance(s)=166.0ftdistance (s) = 166.0 ft
  • finalvelocity(v)=18.9000ft/sfinal velocity (v) = 18.9000 ft/s

Find

acceleration (a), in ft/s²

Start with the thinking

  • The governing relation printed in this handbook section is Constant-acceleration kinematics.
  • 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.
  • Dynamics items reward recognising the unknown before touching a calculator.

Step-by-step solution

  1. Step 1 — State the governing relation:

    v2=v02+2asv^2 = v_0^2 + 2 a s
  2. Step 2 — Rearrange the relation so that a stands alone on the left-hand side.

  3. Step 3 — List the givens: initial velocity (v0) = 54.0000 ft/s, distance (s) = 166.0 ft, final velocity (v) = 18.9000 ft/s.

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

  5. Step 5 — Evaluate:

    a=−7.7072 ft/s²a = -7.7072\ \text{ft/s²}
  6. Step 6 — Check: returning a = -7.7072 ft/s² to

    v2=v02+2asv^2 = v_0^2 + 2 a s

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

Answer:
a=−7.7072 ft/s²a = -7.7072\ \text{ft/s²}

Why the other options are there

  • -15.4144 — kept a factor of two that cancels in the correct rearrangement.
  • -3.8536 — dropped that same factor in the other direction.
  • -8.4779 — rounded an intermediate value before the final step.

Reference: FE Reference Handbook — Dynamics → Concept of Weight

Example 9
Constant-acceleration kinematics — solve for distance (case 3) — Concept of Weight (9)

A dynamics problem uses Constant-acceleration kinematics. Given initial velocity (v0) = 84.0000 ft/s; acceleration (a) = 12.0000 ft/s²; final velocity (v) = 100.6 ft/s, determine the distance (s) in ft.

Given

  • initialvelocity(v0)=84.0000ft/sinitial velocity (v_{0}) = 84.0000 ft/s
  • acceleration(a)=12.0000ft/s2acceleration (a) = 12.0000 ft/s^{2}
  • finalvelocity(v)=100.6ft/sfinal velocity (v) = 100.6 ft/s

Find

distance (s), in ft

Start with the thinking

  • The governing relation printed in this handbook section is Constant-acceleration kinematics.
  • Everything except s is given, so isolate s 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.
  • Dynamics items reward recognising the unknown before touching a calculator.

Step-by-step solution

  1. Step 1 — State the governing relation:

    v2=v02+2asv^2 = v_0^2 + 2 a s
  2. Step 2 — Rearrange the relation so that s stands alone on the left-hand side.

  3. Step 3 — List the givens: initial velocity (v0) = 84.0000 ft/s, acceleration (a) = 12.0000 ft/s², final velocity (v) = 100.6 ft/s.

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

  5. Step 5 — Evaluate:

    s=127.7 fts = 127.7\ \text{ft}
  6. Step 6 — Check: returning s = 127.7 ft to

    v2=v02+2asv^2 = v_0^2 + 2 a s

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

Answer:
s=127.7 fts = 127.7\ \text{ft}

Why the other options are there

  • 255.4 — kept a factor of two that cancels in the correct rearrangement.
  • 63.8408 — dropped that same factor in the other direction.
  • 140.4 — rounded an intermediate value before the final step.

Reference: FE Reference Handbook — Dynamics → Concept of Weight

Example 10
Constant-acceleration kinematics — solve for final velocity (case 4) — Concept of Weight (10)

A dynamics problem uses Constant-acceleration kinematics. Given initial velocity (v0) = 87.0000 ft/s; acceleration (a) = -19.0000 ft/s²; distance (s) = 397.0 ft, determine the final velocity (v) in ft/s.

Given

  • initialvelocity(v0)=87.0000ft/sinitial velocity (v_{0}) = 87.0000 ft/s
  • acceleration(a)=−19.0000ft/s2acceleration (a) = -19.0000 ft/s^{2}
  • distance(s)=397.0ftdistance (s) = 397.0 ft

Find

final velocity (v), in ft/s

Start with the thinking

  • The governing relation printed in this handbook section is Constant-acceleration kinematics.
  • Everything except v is given, so isolate v 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.
  • Dynamics items reward recognising the unknown before touching a calculator.

Step-by-step solution

  1. Step 1 — State the governing relation:

    v2=v02+2asv^2 = v_0^2 + 2 a s
  2. Step 2 — Rearrange the relation so that v stands alone on the left-hand side.

  3. Step 3 — List the givens: initial velocity (v0) = 87.0000 ft/s, acceleration (a) = -19.0000 ft/s², distance (s) = 397.0 ft.

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

  5. Step 5 — Evaluate:

    v=0.0000 ft/sv = 0.0000\ \text{ft/s}
  6. Step 6 — Check: returning v = 0.0000 ft/s to

    v2=v02+2asv^2 = v_0^2 + 2 a s

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

Answer:
v=0.0000 ft/sv = 0.0000\ \text{ft/s}

Why the other options are there

  • 0.0000 — kept a factor of two that cancels in the correct rearrangement.
  • 0.0000 — dropped that same factor in the other direction.
  • 0.0000 — rounded an intermediate value before the final step.

Reference: FE Reference Handbook — Dynamics → Concept of Weight

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