Constant Acceleration
Dynamics · FE Reference Handbook section
Handbook notes for this section
Definitions and conditions exactly as the handbook states them.
- The equations for the velocity and displacement when acceleration is a constant are given as
- An additional equation for velocity as a function of position may be written as
- For constant angular acceleration, the equations for angular velocity and displacement are
- An additional equation for angular velocity as a function of angular position may be written as
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 dynamics problem uses Constant-acceleration kinematics. Given initial velocity (v0) = 83.0000 ft/s; acceleration (a) = -1.5000 ft/s²; distance (s) = 426.0 ft, determine the final velocity (v) in ft/s.
Given
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
Step 1 — State the governing relation:
Step 2 — Rearrange the relation so that v stands alone on the left-hand side.
Step 3 — List the givens: initial velocity (v0) = 83.0000 ft/s, acceleration (a) = -1.5000 ft/s², distance (s) = 426.0 ft.
Step 4 — Substitute the given values into the rearranged relation.
Step 5 — Evaluate:
Step 6 — Check: returning v = 74.9066 ft/s to
reproduces the given quantities, and both sides carry the same units.
Why the other options are there
- 149.8 — kept a factor of two that cancels in the correct rearrangement.
- 37.4533 — dropped that same factor in the other direction.
- 82.3973 — rounded an intermediate value before the final step.
Reference: FE Reference Handbook — Dynamics → Constant Acceleration
An elevator speeds up with constant acceleration before reaching cruise speed. Given initial velocity (v_0) = 43.5000 ft/s; constant acceleration (a) = 13.9000 ft/s^2; time (t) = 9.9000 s, determine the final velocity (v) in ft/s.
Given
Find
final velocity (v), in ft/s
Start with the thinking
- The governing relation printed in this handbook section is Constant acceleration.
- 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.
- Constant acceleration kinematics relates initial velocity, final velocity, acceleration, and time for a particle.
Step-by-step solution
Step 1 — State the governing relation:
Step 2 — Rearrange symbolically for v:
Step 3 — List the givens: initial velocity (v_0) = 43.5000 ft/s, constant acceleration (a) = 13.9000 ft/s^2, time (t) = 9.9000 s.
Step 4 — Substitute the given values:
Step 5 — Evaluate:
Step 6 — Check: returning v = 181.1 ft/s to
reproduces the given quantities, and both sides carry the same units.
Why the other options are there
- 362.2 — kept a factor of two that cancels in the correct rearrangement.
- 90.5550 — dropped that same factor in the other direction.
- 199.2 — rounded an intermediate value before the final step.
Reference: FE Handbook — Dynamics: Constant Acceleration
A dynamics problem uses Constant-acceleration kinematics. Given initial velocity (v0) = 45.0000 ft/s; distance (s) = 58.0000 ft; final velocity (v) = 112.5 ft/s, determine the acceleration (a) in ft/s².
Given
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
Step 1 — State the governing relation:
Step 2 — Rearrange the relation so that a stands alone on the left-hand side.
Step 3 — List the givens: initial velocity (v0) = 45.0000 ft/s, distance (s) = 58.0000 ft, final velocity (v) = 112.5 ft/s.
Step 4 — Substitute the given values into the rearranged relation.
Step 5 — Evaluate:
Step 6 — Check: returning a = 91.6487 ft/s² to
reproduces the given quantities, and both sides carry the same units.
Why the other options are there
- 183.3 — kept a factor of two that cancels in the correct rearrangement.
- 45.8244 — dropped that same factor in the other direction.
- 100.8 — rounded an intermediate value before the final step.
Reference: FE Reference Handbook — Dynamics → Constant Acceleration
A dropped object near Earth's surface undergoes constant acceleration due to gravity. Given constant acceleration (a) = 31.7000 ft/s^2; time (t) = 4.2000 s; final velocity (v) = 143.3 ft/s, determine the initial velocity (v_0) in ft/s.
Given
Find
initial velocity (v_0), in ft/s
Start with the thinking
- The governing relation printed in this handbook section is Constant acceleration.
- Everything except v_0 is given, so isolate v_0 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.
- Constant acceleration kinematics relates initial velocity, final velocity, acceleration, and time for a particle.
Step-by-step solution
Step 1 — State the governing relation:
Step 2 — Rearrange symbolically for v_0:
Step 3 — List the givens: constant acceleration (a) = 31.7000 ft/s^2, time (t) = 4.2000 s, final velocity (v) = 143.3 ft/s.
Step 4 — Substitute the given values:
Step 5 — Evaluate:
Step 6 — Check: returning v_0 = 10.1600 ft/s to
reproduces the given quantities, and both sides carry the same units.
Why the other options are there
- 20.3200 — kept a factor of two that cancels in the correct rearrangement.
- 5.0800 — dropped that same factor in the other direction.
- 11.1760 — rounded an intermediate value before the final step.
Reference: FE Handbook — Dynamics: Constant Acceleration
A dynamics problem uses Constant-acceleration kinematics. Given initial velocity (v0) = 93.0000 ft/s; acceleration (a) = -14.5000 ft/s²; final velocity (v) = 81.0000 ft/s, determine the distance (s) in ft.
Given
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
Step 1 — State the governing relation:
Step 2 — Rearrange the relation so that s stands alone on the left-hand side.
Step 3 — List the givens: initial velocity (v0) = 93.0000 ft/s, acceleration (a) = -14.5000 ft/s², final velocity (v) = 81.0000 ft/s.
Step 4 — Substitute the given values into the rearranged relation.
Step 5 — Evaluate:
Step 6 — Check: returning s = 72.0000 ft to
reproduces the given quantities, and both sides carry the same units.
Why the other options are there
- 144.0 — kept a factor of two that cancels in the correct rearrangement.
- 36.0000 — dropped that same factor in the other direction.
- 79.2000 — rounded an intermediate value before the final step.
Reference: FE Reference Handbook — Dynamics → Constant Acceleration
A car accelerates from a stoplight under constant acceleration. Given initial velocity (v_0) = 32.5000 ft/s; time (t) = 6.0000 s; final velocity (v) = 193.2 ft/s, determine the constant acceleration (a) in ft/s^2.
Given
Find
constant acceleration (a), in ft/s^2
Start with the thinking
- The governing relation printed in this handbook section is Constant acceleration.
- 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.
- Constant acceleration kinematics relates initial velocity, final velocity, acceleration, and time for a particle.
Step-by-step solution
Step 1 — State the governing relation:
Step 2 — Rearrange symbolically for a:
Step 3 — List the givens: initial velocity (v_0) = 32.5000 ft/s, time (t) = 6.0000 s, final velocity (v) = 193.2 ft/s.
Step 4 — Substitute the given values:
Step 5 — Evaluate:
a = 26.7833\ \text{ft/s^2}Step 6 — Check: returning a = 26.7833 ft/s^2 to
reproduces the given quantities, and both sides carry the same units.
Why the other options are there
- 53.5667 — kept a factor of two that cancels in the correct rearrangement.
- 13.3917 — dropped that same factor in the other direction.
- 29.4617 — rounded an intermediate value before the final step.
Reference: FE Handbook — Dynamics: Constant Acceleration
A dynamics problem uses Constant-acceleration kinematics. Given initial velocity (v0) = 23.0000 ft/s; acceleration (a) = 27.0000 ft/s²; distance (s) = 372.0 ft, determine the final velocity (v) in ft/s.
Given
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
Step 1 — State the governing relation:
Step 2 — Rearrange the relation so that v stands alone on the left-hand side.
Step 3 — List the givens: initial velocity (v0) = 23.0000 ft/s, acceleration (a) = 27.0000 ft/s², distance (s) = 372.0 ft.
Step 4 — Substitute the given values into the rearranged relation.
Step 5 — Evaluate:
Step 6 — Check: returning v = 143.6 ft/s to
reproduces the given quantities, and both sides carry the same units.
Why the other options are there
- 287.2 — kept a factor of two that cancels in the correct rearrangement.
- 71.7931 — dropped that same factor in the other direction.
- 157.9 — rounded an intermediate value before the final step.
Reference: FE Reference Handbook — Dynamics → Constant Acceleration
An elevator speeds up with constant acceleration before reaching cruise speed. Given initial velocity (v_0) = 51.5000 ft/s; constant acceleration (a) = 19.2000 ft/s^2; final velocity (v) = 369.9 ft/s, determine the time (t) in s.
Given
Find
time (t), in s
Start with the thinking
- The governing relation printed in this handbook section is Constant acceleration.
- Everything except t is given, so isolate t 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.
- Constant acceleration kinematics relates initial velocity, final velocity, acceleration, and time for a particle.
Step-by-step solution
Step 1 — State the governing relation:
Step 2 — Rearrange symbolically for t:
Step 3 — List the givens: initial velocity (v_0) = 51.5000 ft/s, constant acceleration (a) = 19.2000 ft/s^2, final velocity (v) = 369.9 ft/s.
Step 4 — Substitute the given values:
Step 5 — Evaluate:
Step 6 — Check: returning t = 16.5833 s to
reproduces the given quantities, and both sides carry the same units.
Why the other options are there
- 33.1667 — kept a factor of two that cancels in the correct rearrangement.
- 8.2917 — dropped that same factor in the other direction.
- 18.2417 — rounded an intermediate value before the final step.
Reference: FE Handbook — Dynamics: Constant Acceleration
A dynamics problem uses Constant-acceleration kinematics. Given initial velocity (v0) = 78.0000 ft/s; distance (s) = 367.0 ft; final velocity (v) = 9.0000 ft/s, determine the acceleration (a) in ft/s².
Given
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
Step 1 — State the governing relation:
Step 2 — Rearrange the relation so that a stands alone on the left-hand side.
Step 3 — List the givens: initial velocity (v0) = 78.0000 ft/s, distance (s) = 367.0 ft, final velocity (v) = 9.0000 ft/s.
Step 4 — Substitute the given values into the rearranged relation.
Step 5 — Evaluate:
Step 6 — Check: returning a = -8.1785 ft/s² to
reproduces the given quantities, and both sides carry the same units.
Why the other options are there
- -16.3569 — kept a factor of two that cancels in the correct rearrangement.
- -4.0892 — dropped that same factor in the other direction.
- -8.9963 — rounded an intermediate value before the final step.
Reference: FE Reference Handbook — Dynamics → Constant Acceleration
A dropped object near Earth's surface undergoes constant acceleration due to gravity. Given initial velocity (v_0) = 35.5000 ft/s; constant acceleration (a) = 7.0000 ft/s^2; time (t) = 1.9000 s, determine the final velocity (v) in ft/s.
Given
Find
final velocity (v), in ft/s
Start with the thinking
- The governing relation printed in this handbook section is Constant acceleration.
- 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.
- Constant acceleration kinematics relates initial velocity, final velocity, acceleration, and time for a particle.
Step-by-step solution
Step 1 — State the governing relation:
Step 2 — Rearrange symbolically for v:
Step 3 — List the givens: initial velocity (v_0) = 35.5000 ft/s, constant acceleration (a) = 7.0000 ft/s^2, time (t) = 1.9000 s.
Step 4 — Substitute the given values:
Step 5 — Evaluate:
Step 6 — Check: returning v = 48.8000 ft/s to
reproduces the given quantities, and both sides carry the same units.
Why the other options are there
- 97.6000 — kept a factor of two that cancels in the correct rearrangement.
- 24.4000 — dropped that same factor in the other direction.
- 53.6800 — rounded an intermediate value before the final step.
Reference: FE Handbook — Dynamics: Constant Acceleration