Radial and Transverse Components for Planar Motion
Dynamics · 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 radar tracks an aircraft using radial and transverse velocity components. Given radial distance (r) = 13.1000 ft; angular rate (theta_dot) = 1.1000 rad/s; radial velocity (r_dot) = 19.0000 ft/s, determine the transverse velocity (v_theta) in ft/s.
Given
Find
transverse velocity (v_theta), in ft/s
Start with the thinking
- The governing relation printed in this handbook section is Radial and transverse velocity components.
- Everything except v_theta is given, so isolate v_theta 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.
- Radial and transverse components for planar motion describe a particle's velocity in polar coordinates.
Figure 1 — schematic for Radial and transverse velocity components — solve for transverse velocity — Radial and Transverse Components for Planar Motion
Step-by-step solution
Step 1 — State the governing relation:
Step 2 — Rearrange symbolically for v_theta:
Step 3 — List the givens: radial distance (r) = 13.1000 ft, angular rate (theta_dot) = 1.1000 rad/s, radial velocity (r_dot) = 19.0000 ft/s.
Step 4 — Substitute the given values:
Step 5 — Evaluate:
Step 6 — Check: returning v_theta = 14.4100 ft/s to
reproduces the given quantities, and both sides carry the same units.
Why the other options are there
- 28.8200 — kept a factor of two that cancels in the correct rearrangement.
- 7.2050 — dropped that same factor in the other direction.
- 15.8510 — rounded an intermediate value before the final step.
Reference: FE Handbook — Dynamics: Radial and Transverse Components for Planar Motion
A particle sliding in a rotating slot is analyzed with radial and transverse components. Given angular rate (theta_dot) = 4.8500 rad/s; transverse velocity (v_theta) = 4.3000 ft/s; radial velocity (r_dot) = 8.1000 ft/s, determine the radial distance (r) in ft.
Given
Find
radial distance (r), in ft
Start with the thinking
- The governing relation printed in this handbook section is Radial and transverse velocity components.
- Everything except r is given, so isolate r 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.
- Radial and transverse components for planar motion describe a particle's velocity in polar coordinates.
Figure 2 — schematic for Radial and transverse velocity components — solve for radial distance — Radial and Transverse Components for Planar Motion (2)
Step-by-step solution
Step 1 — State the governing relation:
Step 2 — Rearrange symbolically for r:
Step 3 — List the givens: angular rate (theta_dot) = 4.8500 rad/s, transverse velocity (v_theta) = 4.3000 ft/s, radial velocity (r_dot) = 8.1000 ft/s.
Step 4 — Substitute the given values:
Step 5 — Evaluate:
Step 6 — Check: returning r = 0.8866 ft to
reproduces the given quantities, and both sides carry the same units.
Why the other options are there
- 1.7732 — kept a factor of two that cancels in the correct rearrangement.
- 0.4433 — dropped that same factor in the other direction.
- 0.9753 — rounded an intermediate value before the final step.
Reference: FE Handbook — Dynamics: Radial and Transverse Components for Planar Motion
A satellite's planar motion is decomposed into radial and transverse components. Given radial distance (r) = 4.3000 ft; transverse velocity (v_theta) = 18.9000 ft/s; radial velocity (r_dot) = 11.5000 ft/s, determine the angular rate (theta_dot) in rad/s.
Given
Find
angular rate (theta_dot), in rad/s
Start with the thinking
- The governing relation printed in this handbook section is Radial and transverse velocity components.
- Everything except theta_dot is given, so isolate theta_dot 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.
- Radial and transverse components for planar motion describe a particle's velocity in polar coordinates.
Figure 3 — schematic for Radial and transverse velocity components — solve for angular rate — Radial and Transverse Components for Planar Motion (3)
Step-by-step solution
Step 1 — State the governing relation:
Step 2 — Rearrange symbolically for theta_dot:
Step 3 — List the givens: radial distance (r) = 4.3000 ft, transverse velocity (v_theta) = 18.9000 ft/s, radial velocity (r_dot) = 11.5000 ft/s.
Step 4 — Substitute the given values:
Step 5 — Evaluate:
Step 6 — Check: returning theta_dot = 4.3953 rad/s to
reproduces the given quantities, and both sides carry the same units.
Why the other options are there
- 8.7907 — kept a factor of two that cancels in the correct rearrangement.
- 2.1977 — dropped that same factor in the other direction.
- 4.8349 — rounded an intermediate value before the final step.
Reference: FE Handbook — Dynamics: Radial and Transverse Components for Planar Motion
A radar tracks an aircraft using radial and transverse velocity components. Given radial distance (r) = 4.0000 ft; angular rate (theta_dot) = 2.8000 rad/s; radial velocity (r_dot) = 12.7000 ft/s, determine the transverse velocity (v_theta) in ft/s.
Given
Find
transverse velocity (v_theta), in ft/s
Start with the thinking
- The governing relation printed in this handbook section is Radial and transverse velocity components.
- Everything except v_theta is given, so isolate v_theta 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.
- Radial and transverse components for planar motion describe a particle's velocity in polar coordinates.
Figure 4 — schematic for Radial and transverse velocity components — solve for transverse velocity (case 2) — Radial and Transverse Components for Planar Motion (4)
Step-by-step solution
Step 1 — State the governing relation:
Step 2 — Rearrange symbolically for v_theta:
Step 3 — List the givens: radial distance (r) = 4.0000 ft, angular rate (theta_dot) = 2.8000 rad/s, radial velocity (r_dot) = 12.7000 ft/s.
Step 4 — Substitute the given values:
Step 5 — Evaluate:
Step 6 — Check: returning v_theta = 11.2000 ft/s to
reproduces the given quantities, and both sides carry the same units.
Why the other options are there
- 22.4000 — kept a factor of two that cancels in the correct rearrangement.
- 5.6000 — dropped that same factor in the other direction.
- 12.3200 — rounded an intermediate value before the final step.
Reference: FE Handbook — Dynamics: Radial and Transverse Components for Planar Motion
A particle sliding in a rotating slot is analyzed with radial and transverse components. Given angular rate (theta_dot) = 1.7500 rad/s; transverse velocity (v_theta) = 52.8000 ft/s; radial velocity (r_dot) = 1.6000 ft/s, determine the radial distance (r) in ft.
Given
Find
radial distance (r), in ft
Start with the thinking
- The governing relation printed in this handbook section is Radial and transverse velocity components.
- Everything except r is given, so isolate r 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.
- Radial and transverse components for planar motion describe a particle's velocity in polar coordinates.
Figure 5 — schematic for Radial and transverse velocity components — solve for radial distance (case 2) — Radial and Transverse Components for Planar Motion (5)
Step-by-step solution
Step 1 — State the governing relation:
Step 2 — Rearrange symbolically for r:
Step 3 — List the givens: angular rate (theta_dot) = 1.7500 rad/s, transverse velocity (v_theta) = 52.8000 ft/s, radial velocity (r_dot) = 1.6000 ft/s.
Step 4 — Substitute the given values:
Step 5 — Evaluate:
Step 6 — Check: returning r = 30.1714 ft to
reproduces the given quantities, and both sides carry the same units.
Why the other options are there
- 60.3429 — kept a factor of two that cancels in the correct rearrangement.
- 15.0857 — dropped that same factor in the other direction.
- 33.1886 — rounded an intermediate value before the final step.
Reference: FE Handbook — Dynamics: Radial and Transverse Components for Planar Motion
A satellite's planar motion is decomposed into radial and transverse components. Given radial distance (r) = 8.4000 ft; transverse velocity (v_theta) = 20.7000 ft/s; radial velocity (r_dot) = 2.8000 ft/s, determine the angular rate (theta_dot) in rad/s.
Given
Find
angular rate (theta_dot), in rad/s
Start with the thinking
- The governing relation printed in this handbook section is Radial and transverse velocity components.
- Everything except theta_dot is given, so isolate theta_dot 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.
- Radial and transverse components for planar motion describe a particle's velocity in polar coordinates.
Figure 6 — schematic for Radial and transverse velocity components — solve for angular rate (case 2) — Radial and Transverse Components for Planar Motion (6)
Step-by-step solution
Step 1 — State the governing relation:
Step 2 — Rearrange symbolically for theta_dot:
Step 3 — List the givens: radial distance (r) = 8.4000 ft, transverse velocity (v_theta) = 20.7000 ft/s, radial velocity (r_dot) = 2.8000 ft/s.
Step 4 — Substitute the given values:
Step 5 — Evaluate:
Step 6 — Check: returning theta_dot = 2.4643 rad/s to
reproduces the given quantities, and both sides carry the same units.
Why the other options are there
- 4.9286 — kept a factor of two that cancels in the correct rearrangement.
- 1.2321 — dropped that same factor in the other direction.
- 2.7107 — rounded an intermediate value before the final step.
Reference: FE Handbook — Dynamics: Radial and Transverse Components for Planar Motion
A radar tracks an aircraft using radial and transverse velocity components. Given radial distance (r) = 5.7000 ft; angular rate (theta_dot) = 2.4000 rad/s; radial velocity (r_dot) = 17.7000 ft/s, determine the transverse velocity (v_theta) in ft/s.
Given
Find
transverse velocity (v_theta), in ft/s
Start with the thinking
- The governing relation printed in this handbook section is Radial and transverse velocity components.
- Everything except v_theta is given, so isolate v_theta 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.
- Radial and transverse components for planar motion describe a particle's velocity in polar coordinates.
Figure 7 — schematic for Radial and transverse velocity components — solve for transverse velocity (case 3) — Radial and Transverse Components for Planar Motion (7)
Step-by-step solution
Step 1 — State the governing relation:
Step 2 — Rearrange symbolically for v_theta:
Step 3 — List the givens: radial distance (r) = 5.7000 ft, angular rate (theta_dot) = 2.4000 rad/s, radial velocity (r_dot) = 17.7000 ft/s.
Step 4 — Substitute the given values:
Step 5 — Evaluate:
Step 6 — Check: returning v_theta = 13.6800 ft/s to
reproduces the given quantities, and both sides carry the same units.
Why the other options are there
- 27.3600 — kept a factor of two that cancels in the correct rearrangement.
- 6.8400 — dropped that same factor in the other direction.
- 15.0480 — rounded an intermediate value before the final step.
Reference: FE Handbook — Dynamics: Radial and Transverse Components for Planar Motion
A particle sliding in a rotating slot is analyzed with radial and transverse components. Given angular rate (theta_dot) = 3.2000 rad/s; transverse velocity (v_theta) = 47.0000 ft/s; radial velocity (r_dot) = 11.9000 ft/s, determine the radial distance (r) in ft.
Given
Find
radial distance (r), in ft
Start with the thinking
- The governing relation printed in this handbook section is Radial and transverse velocity components.
- Everything except r is given, so isolate r 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.
- Radial and transverse components for planar motion describe a particle's velocity in polar coordinates.
Figure 8 — schematic for Radial and transverse velocity components — solve for radial distance (case 3) — Radial and Transverse Components for Planar Motion (8)
Step-by-step solution
Step 1 — State the governing relation:
Step 2 — Rearrange symbolically for r:
Step 3 — List the givens: angular rate (theta_dot) = 3.2000 rad/s, transverse velocity (v_theta) = 47.0000 ft/s, radial velocity (r_dot) = 11.9000 ft/s.
Step 4 — Substitute the given values:
Step 5 — Evaluate:
Step 6 — Check: returning r = 14.6875 ft to
reproduces the given quantities, and both sides carry the same units.
Why the other options are there
- 29.3750 — kept a factor of two that cancels in the correct rearrangement.
- 7.3438 — dropped that same factor in the other direction.
- 16.1563 — rounded an intermediate value before the final step.
Reference: FE Handbook — Dynamics: Radial and Transverse Components for Planar Motion
A satellite's planar motion is decomposed into radial and transverse components. Given radial distance (r) = 8.3000 ft; transverse velocity (v_theta) = 35.3000 ft/s; radial velocity (r_dot) = 16.7000 ft/s, determine the angular rate (theta_dot) in rad/s.
Given
Find
angular rate (theta_dot), in rad/s
Start with the thinking
- The governing relation printed in this handbook section is Radial and transverse velocity components.
- Everything except theta_dot is given, so isolate theta_dot 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.
- Radial and transverse components for planar motion describe a particle's velocity in polar coordinates.
Figure 9 — schematic for Radial and transverse velocity components — solve for angular rate (case 3) — Radial and Transverse Components for Planar Motion (9)
Step-by-step solution
Step 1 — State the governing relation:
Step 2 — Rearrange symbolically for theta_dot:
Step 3 — List the givens: radial distance (r) = 8.3000 ft, transverse velocity (v_theta) = 35.3000 ft/s, radial velocity (r_dot) = 16.7000 ft/s.
Step 4 — Substitute the given values:
Step 5 — Evaluate:
Step 6 — Check: returning theta_dot = 4.2530 rad/s to
reproduces the given quantities, and both sides carry the same units.
Why the other options are there
- 8.5060 — kept a factor of two that cancels in the correct rearrangement.
- 2.1265 — dropped that same factor in the other direction.
- 4.6783 — rounded an intermediate value before the final step.
Reference: FE Handbook — Dynamics: Radial and Transverse Components for Planar Motion
A radar tracks an aircraft using radial and transverse velocity components. Given radial distance (r) = 9.7000 ft; angular rate (theta_dot) = 4.0000 rad/s; radial velocity (r_dot) = 6.8000 ft/s, determine the transverse velocity (v_theta) in ft/s.
Given
Find
transverse velocity (v_theta), in ft/s
Start with the thinking
- The governing relation printed in this handbook section is Radial and transverse velocity components.
- Everything except v_theta is given, so isolate v_theta 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.
- Radial and transverse components for planar motion describe a particle's velocity in polar coordinates.
Figure 10 — schematic for Radial and transverse velocity components — solve for transverse velocity (case 4) — Radial and Transverse Components for Planar Motion (10)
Step-by-step solution
Step 1 — State the governing relation:
Step 2 — Rearrange symbolically for v_theta:
Step 3 — List the givens: radial distance (r) = 9.7000 ft, angular rate (theta_dot) = 4.0000 rad/s, radial velocity (r_dot) = 6.8000 ft/s.
Step 4 — Substitute the given values:
Step 5 — Evaluate:
Step 6 — Check: returning v_theta = 38.8000 ft/s to
reproduces the given quantities, and both sides carry the same units.
Why the other options are there
- 77.6000 — kept a factor of two that cancels in the correct rearrangement.
- 19.4000 — dropped that same factor in the other direction.
- 42.6800 — rounded an intermediate value before the final step.
Reference: FE Handbook — Dynamics: Radial and Transverse Components for Planar Motion