Dynamics: how 9 AI study apps did on 11 college problems
Covers kinematics, Newton's laws, work-energy, impulse-momentum, rigid-body kinetics. Every app got the same problem text in a fresh chat, one attempt, no hints. Tested October 18, 2026 – October 19, 2026.
| Rank | App | Accuracy | Problems graded |
|---|---|---|---|
| 1 | Claude | 93.9% | 11 / 11 |
| 2 | MyStudySidekick | 90.9% | 11 / 11 |
| 3 | ChatGPT | 81.8% | 11 / 11 |
| 4 | Solvely | 57.6% | 11 / 11 |
| 5 | NotebookLM | 48.5% | 11 / 11 |
| 6 | Turbo AI | 18.2% | 11 / 11 |
| 7 | StudyFetch | 9.1% | 11 / 11 |
| 8 | Quizlet | 3.0% | 11 / 11 |
| 9 | Knowt | 1.5% | 11 / 11 |
The team behind MyStudySidekick runs this benchmark (disclosure and safeguards). Models used: ChatGPT, GPT-6, high reasoning effort; Claude, Claude Opus 5.5, medium effort. Problems reprinted from a textbook are listed by citation only; apps received a photo of the printed problem.
Every problem, the key, and each app's answer
- 1. Motor-driven gear with three pinned pinions: angular velocity after 2 s
- 2. Automobile differential: angular velocity of each axle
- 3. Rod between two collars: speed of collar B on an inclined rod
- 4. Crank-driven rod: acceleration of collar A
- 5. X-ray camera on a rotating frame: velocity and acceleration of C
- 6. Locomotive crane: velocity and acceleration of the boom tip
- 7. Bent rod: moments of inertia about x, y, z
- 8. Rod, collar and link released from rest: link's angular velocity after 180°
- 9. Rod assembly on a ball-and-socket: angular velocity after an impulse
- 10. Disk rolling on the ground around a vertical shaft: normal and friction force
- 11. Rocket struck by a meteoroid: axis of precession
Problem 1
Motor-driven gear with three pinned pinions: angular velocity after 2 s
angular impulse and momentum (gear trains)
Textbook problem, listed by citation only: R.C. Hibbeler, Engineering Mechanics: Dynamics, 14th ed. (Pearson, 2016), Prob. 19–23, as printed. Back-of-book answer ω_B = 127 rad/s.
| App | (a) angular velocity of each smaller gear B | Score |
|---|---|---|
| Answer key | 126.7 rad/s ±1% | |
| StudyFetch | 127 rad/s | 100% |
| Turbo AI | 127 rad/s | 100% |
| Solvely | 127 rad/s | 100% |
| NotebookLM | 126.68 rad/s | 100% |
| ChatGPT | 126.7 rad/s | 100% |
| Claude | 126.7 rad/s | 100% |
| MyStudySidekick | 126.678 rad/s | 100% |
| Quizlet | 170.4 rad/s | 0% |
| Why: Wrong: treated the four gears as one system about one axis (M t = I_A ω_A + 3 I_B ω_B), missing the gear-ratio factor on the tooth impulses; 6 I_B instead of 12 I_B. | ||
| Knowt | 268.7 rad/s | 0% |
| Why: Wrong: ignored the B gears' inertia (α_A = M/I_A) and used the radii of gyration as pitch radii. | ||
Problem 2
Automobile differential: angular velocity of each axle
3D rigid-body kinematics (gears turning about non-parallel axes)
Textbook problem, listed by citation only: R.C. Hibbeler, Engineering Mechanics: Dynamics, 14th ed. (Pearson, 2016), Prob. 20–23, as printed. Back-of-book answer ω_A = 47.8 rad/s, ω_B = 7.78 rad/s.
| App | (a) ω_A (left axle) | (b) ω_B (right axle) | Score |
|---|---|---|---|
| Answer key | 47.78 rad/s ±1% | 7.778 rad/s ±1% | |
| Turbo AI | 47.8 rad/s | 7.78 rad/s | 100% |
| Solvely | 47.8 rad/s | 7.78 rad/s | 100% |
| NotebookLM | 47.8 rad/s | 7.78 rad/s | 100% |
| ChatGPT | 47.8 rad/s | 7.78 rad/s | 100% |
| Claude | 47.8 rad/s | 7.78 rad/s | 100% |
| MyStudySidekick | 47.7778 rad/s | 7.7778 rad/s | 100% |
| Quizlet | 7.78 rad/s | 47.78 rad/s | 0% |
| Why: Wrong: right speeds on the wrong axles. It found the case speed (27.78 rad/s) and the ±20 rad/s split, but assumed which way E's spin acts instead of reading it from the figure, so A and B are swapped. It also wrote 'assuming the gear ratio between E and A/B is 1:1' and then used 40/60. | |||
| Knowt | 243.33 rad/s | 183.33 rad/s | 0% |
| Why: Wrong: invented a gear formula, ω_G = (ω_H r_G + ω_E r_E)/(r_H + r_E) = 213 rad/s for the ring gear (true value 27.8), then added and subtracted 30 rad/s. | |||
| StudyFetch | No answer | No answer | 0% |
| Why: The tester reported the app could not solve it; scored 0. | |||
Problem 3
Rod between two collars: speed of collar B on an inclined rod
3D rigid-body kinematics (rod with ball-and-socket ends)
Textbook problem, listed by citation only: R.C. Hibbeler, Engineering Mechanics: Dynamics, 14th ed. (Pearson, 2016), Prob. 20–25, as printed. Key from the worked solution shared by the owner, checked by an independent vector solve.
| App | (a) speed of collar B | Score |
|---|---|---|
| Answer key | 3.2 m/s ±1% | |
| ChatGPT | no final answer | 100% |
| Claude | 3.20 m/s | 100% |
| MyStudySidekick | speed_B = 3.2 m/s | 100% |
| Quizlet | No answer | 0% |
| Why: No answer: misread the geometry (A on the z axis, B at (1, 1.5, 1.5)), lost track of B's guide rod mid-solution ('wait, looking closer at the diagram…') and stopped without a number. | ||
| Knowt | 8 m/s | 0% |
| Why: Wrong: no 3D geometry at all. Took the rod as 2.5 m from a 2-by-1.5 triangle and added v_A to L·(v_A/L): 4 + 4 = 8 m/s instead of 3.2. | ||
| StudyFetch | Error | 0% |
| Why: The tester reported the app errored out on this problem; scored 0. | ||
| Turbo AI | Error | 0% |
| Why: The tester reported the app errored out on this problem; scored 0. | ||
| Solvely | 2.50 m/s | 0% |
| Why: Wrong: misread the geometry. Put A's rod at x = 1.5 m (A's rod is at x = 1 m; the 1.5 m runs along y) and B's rod running to y = 2.5 m, so r_B/A = −1.5 i + 1 j − 0.8 k; 2.50 instead of 3.2 m/s. | ||
| NotebookLM | 8 m/s | 0% |
| Why: Wrong: misread the geometry. Took B's rod as horizontal along y at z = 0 and A 2 m above it (r_B/A = −1.5 i + 1 j − 2 k), and v_A downward; the 1.5 m runs along the inclined rod. Got 8 m/s instead of 3.2. | ||
Problem 4
Crank-driven rod: acceleration of collar A
3D rigid-body kinematics (acceleration, rod with ball-and-socket ends)
Textbook problem, listed by citation only: R.C. Hibbeler, Engineering Mechanics: Dynamics, 14th ed. (Pearson, 2016), Prob. 20–29, as printed. Key from the worked solution shared by the owner, checked by an independent vector solve.
| App | (a) acceleration of collar A (z component) | Score |
|---|---|---|
| Answer key | −13.87 m/s^2 ±1% | |
| Claude | −13.9 m/s² (k) | 100% |
| MyStudySidekick | aA_z = −13.8656 m/s² | 100% |
| Quizlet | No answer | 0% |
| Why: No answer: misread the geometry (B at 0.3 j, A at x = 0.3, y = 0.8, took the 1000 mm as the rod's length), set up the method and stopped ('by solving the system… we find'), recommending the student verify the algebra. | ||
| Knowt | 28.8 m/s² (magnitude) | 0% |
| Why: Wrong: treated collar A as a point on crank BC turning at 6 rad/s with radius 0.8 m (the 800 mm is A's height), so it reported ω²r = 28.8 m/s² instead of −13.9 m/s². | ||
| StudyFetch | a_A = 4.05 m/s² upward (+z) | 0% |
| Why: Wrong: put B at (0, 0.3, 0) and A at (0, −0.3, 0.8) and took the 1000 mm as the rod's length (a 600–800–1000 triangle), so the collar came out momentarily at rest; 4.05 m/s² upward instead of 13.9 m/s² downward. The app had errored out on the first try; this answer came on a later try (2026-10-19). Response text in the screenshots. | ||
| Turbo AI | a_A = −9.82 k m/s² | 0% |
| Why: Wrong: B and C mixed up. Put the crank's fixed shaft C on the y axis (x = 0) and B 0.3 m along −x from it, so B = (−0.3, 1, 0) and the rod lay in the plane x = −0.3 (B is at (0, 1, 0); the crank runs from C at x = 0.3 to B on the y axis). Method right, geometry wrong: −9.82 instead of −13.9 m/s². | ||
| Solvely | a_A = −3.49 k m/s² | 0% |
| Why: Wrong: misread where A is. Put A's rod 300 mm along y (it is 300 mm along x) and B at 0.3 i + 1.0 j, so r_A/B = −0.3 i − 0.7 j + 0.8 k; −3.49 instead of −13.9 m/s². (MyStudySidekick's Gemini reads made the same misreading, −3.495, before its figure check caught it.) | ||
| NotebookLM | a_A = −0.401 k m/s² | 0% |
| Why: Wrong: misread where B and A are. Put B at 0.3 i from C and A at y = 0.3 m (r_B/A = 0.3 i − 0.3 j − 0.8 k), ignoring the 1000 mm to B, so a_A = −0.401 instead of −13.9 m/s². | ||
| ChatGPT | a_A = −9.82 k m/s² (9.82 m/s² downward) | 0% |
| Why: Wrong: read the two 300 mm offsets as equal, so it put rod AB in a plane parallel to y–z (r_B/A = 1.0 j − 0.8 k), the same B/C mix-up as Turbo AI; −9.82 instead of −13.9 m/s². Worked 2 m 20 s. Response text in the screenshots. | ||
Problem 5
X-ray camera on a rotating frame: velocity and acceleration of C
3D kinematics with translating and rotating axes
Textbook problem, listed by citation only: R.C. Hibbeler, Engineering Mechanics: Dynamics, 14th ed. (Pearson, 2016), Prob. 20–49, as printed. Key from the worked solution shared by the owner, checked by an independent vector solve.
| App | (a) v_C, x component | (b) v_C, y component | (c) v_C, z component | (d) a_C, x component | (e) a_C, y component | (f) a_C, z component | Score |
|---|---|---|---|---|---|---|---|
| Answer key | −6.75 m/s ±1% | −6.25 m/s ±1% | 0 m/s ±0.05 m/s | 28.75 m/s^2 ±1% | −26.25 m/s^2 ±1% | −4 m/s^2 ±1% | |
| ChatGPT | no final answer | no final answer | no final answer | no final answer | no final answer | no final answer | 100% |
| MyStudySidekick | vC = −6.75 i − 6.25 j + 0 k m/s; aC = 28.75 i − 26.25 j − 4 k m/s² | (see part a) | (see part a) | (see part a) | (see part a) | (see part a) | 100% |
| NotebookLM | v_C = −13 i m/s; a_C = −5 i − 55 j − 4 k m/s² | (see part a) | (see part a) | (see part a) | (see part a) | (see part a) | 33% |
| Why: Wrong: same misreading as Claude. Put C at y = 1.25 + 1.75 = 3 m on the y axis (x = 0), adding a dimension that runs along x into y; only the two z components match. | |||||||
| Claude | v_C = −13.0 i m/s; a_C = −5.00 i − 55.0 j − 4.00 k m/s² | (see part a) | (see part a) | (see part a) | (see part a) | (see part a) | 33% |
| Why: Wrong: misread where C is. Added the 1.25 m dimension along y (C at y = 3 m, x = 0, z = 2.25 m) instead of along x, so v_C lost its y component (−13.0 i instead of −6.75 i − 6.25 j) and a_C came out −5 i − 55 j − 4 k. Only the two z components match. | |||||||
| Knowt | v_C = −12.25 i + 8.75 j m/s; a_C = 57.75 i + 93.625 j m/s² | (see part a) | (see part a) | (see part a) | (see part a) | (see part a) | 17% |
| Why: Wrong: put both rotations about the vertical axis (ω = 5 + 2 = 7 rad/s about z), ignored the 1 m height of C, and added the centripetal term with the wrong sign; only v_z = 0 matches. | |||||||
| Quizlet | v_C = 2 i + 15 j − 6 k m/s; a_C = −86 i + 26 j − 7 k m/s² | (see part a) | (see part a) | (see part a) | (see part a) | (see part a) | 0% |
| Why: Wrong: put C at 3 i + 1 k m (both dimensions added along x) and turned the arm about A; no component matches. | |||||||
| StudyFetch | Error | Error | Error | Error | Error | Error | 0% |
| Why: The tester reported the app errored out on this problem; scored 0. | |||||||
| Turbo AI | Error | Error | Error | Error | Error | Error | 0% |
| Why: The tester reported the app errored out on this problem; scored 0. | |||||||
| Solvely | v_C = −15.0 i + 6.25 j − 6.25 k m/s; a_C = −65.25 i − 90.0 j − 12.5 k m/s² | (see part a) | (see part a) | (see part a) | (see part a) | (see part a) | 0% |
| Why: Wrong: put C at (+1.25, 3, 1) m (the 1.25 m added along y and also placed on +x) and treated A as the fixed point of the whole rotation. Its 'Final Answer' also disagrees with its own working (−13 i + 6.25 j − 2.5 k; −41.25 i − 52.5 j − 5.25 k). No component matches. | |||||||
Problem 6
Locomotive crane: velocity and acceleration of the boom tip
3D kinematics with translating and rotating axes
Textbook problem, listed by citation only: R.C. Hibbeler, Engineering Mechanics: Dynamics, 14th ed. (Pearson, 2016), Prob. 20–51, as printed. Key from the worked solution shared by the owner, checked by an independent vector solve.
| App | (a) v_B, x component | (b) v_B, y component | (c) v_B, z component | (d) a_B, x component | (e) a_B, y component | (f) a_B, z component | Score |
|---|---|---|---|---|---|---|---|
| Answer key | −10.16 m/s ±1% | −28 m/s ±1% | 51.96 m/s ±1% | −30.96 m/s^2 ±1% | −159.5 m/s^2 ±1% | −90 m/s^2 ±1% | |
| NotebookLM | v_B = −10.2 i − 28.0 j + 52.0 k m/s; a_B = −31.0 i − 159.5 j − 90.0 k m/s² | (see part a) | (see part a) | (see part a) | (see part a) | (see part a) | 100% |
| ChatGPT | no final answer | no final answer | no final answer | no final answer | no final answer | no final answer | 100% |
| Claude | v_B = −10.2 i − 28.0 j + 52.0 k m/s; a_B = −31.0 i − 159 j − 90.0 k m/s² | (see part a) | (see part a) | (see part a) | (see part a) | (see part a) | 100% |
| MyStudySidekick | vB = −10.1603 i − 28 j + 51.9615 k m/s; aB = −30.9615 i − 159.465 j − 90 k m/s² | (see part a) | (see part a) | (see part a) | (see part a) | (see part a) | 100% |
| Quizlet | v_B = −8.66 i + 32 j − 51.96 k m/s; a_B = −81.96 i − 158.71 j − 90 k m/s² | (see part a) | (see part a) | (see part a) | (see part a) | (see part a) | 33% |
| Why: Wrong: measured B from pin A but left out the 3 m from the z axis to A in Ω × r, got the relative velocity's signs backwards (+30 j − 51.96 k), and the Coriolis term's sign flipped with it; only a_y and a_z match. | |||||||
| Solvely | v_B = −10.2 i + 32.0 j − 61.0 k m/s; a_B = −91.0 i − 186 j − 90.0 k m/s² | (see part a) | (see part a) | (see part a) | (see part a) | (see part a) | 33% |
| Why: Wrong: took the boom's rise as −3 i (rising from +y toward +z is +3 i) and applied it about O instead of about pin A; only v_x and a_z match. | |||||||
| Knowt | v_B = −8 i − 30√3 j m/s; acceleration not computed | (see part a) | (see part a) | (see part a) | (see part a) | (see part a) | 0% |
| Why: Wrong: placed the boom in the x–y plane with no z component, left out ω1 entirely, and never computed the acceleration ('to be calculated'). | |||||||
| StudyFetch | Error | Error | Error | Error | Error | Error | 0% |
| Why: The tester reported the app errored out on this problem; scored 0. | |||||||
| Turbo AI | Error | Error | Error | Error | Error | Error | 0% |
| Why: The tester reported the app errored out on this problem; scored 0. | |||||||
Problem 7
Bent rod: moments of inertia about x, y, z
moments of inertia of a composite body
Textbook problem, listed by citation only: R.C. Hibbeler, Engineering Mechanics: Dynamics, 14th ed. (Pearson, 2016), Prob. 21–13, as printed. Key from the worked solution shared by the owner, checked by an independent vector solve.
| App | (a) Ixx | (b) Iyy | (c) Izz | Score |
|---|---|---|---|---|
| Answer key | 0.626 kg·m^2 ±1% | 0.547 kg·m^2 ±1% | 1.09 kg·m^2 ±1% | |
| Solvely | Ixx 0.626, Iyy 0.547, Izz 1.09 kg·m² | (see part a) | (see part a) | 100% |
| NotebookLM | Ixx 0.626, Iyy 0.547, Izz 1.087 kg·m² | (see part a) | (see part a) | 100% |
| ChatGPT | no final answer | no final answer | no final answer | 100% |
| Claude | Ixx 0.626, Iyy 0.547, Izz 1.09 kg·m² | (see part a) | (see part a) | 100% |
| MyStudySidekick | Ixx 0.626, Iyy 0.5467, Izz 1.0873 kg·m² | (see part a) | (see part a) | 100% |
| Quizlet | Ixx 0.0427, Iyy 0.2315, Izz 0.2208 kg·m² (given as 42 667, 231 500, 220 833 kg·mm²) | (see part a) | (see part a) | 0% |
| Why: Wrong: saw only two segments (500 mm along x, 400 mm along z) and missed the 600 mm segment entirely. | ||||
| Knowt | Ixx 0.3015 kg·m²; Iyy and Izz not computed | (see part a) | (see part a) | 0% |
| Why: Wrong: took moments about the composite centroid instead of the x, y, z axes, drew the rod as a 2D shape, and left Iyy and Izz as '…'; I_zz = I_xx + I_yy is only true for a flat plate. | ||||
| StudyFetch | Error | Error | Error | 0% |
| Why: The tester reported the app errored out on this problem; scored 0. | ||||
| Turbo AI | Error | Error | Error | 0% |
| Why: The tester reported the app errored out on this problem; scored 0. | ||||
Problem 8
Rod, collar and link released from rest: link's angular velocity after 180°
3D kinetic energy and conservation of energy
Textbook problem, listed by citation only: R.C. Hibbeler, Engineering Mechanics: Dynamics, 14th ed. (Pearson, 2016), Prob. 21–27, as printed. Key from the worked solution shared by the owner, checked by an independent vector solve.
| App | (a) angular velocity of link BC | Score |
|---|---|---|
| Answer key | 10.85 rad/s ±1% | |
| ChatGPT | no final answer | 100% |
| Claude | 10.8 rad/s | 100% |
| MyStudySidekick | ω_BC = 10.8499 rad/s | 100% |
| Quizlet | No answer | 0% |
| Why: No answer: outlined conservation of energy, then handed the problem back to the student ('Can you identify the position of the center of mass…?'). | ||
| Knowt | No answer | 0% |
| Why: No answer: took BC as 1.3 m and AB as 1.2 m, counted only the rod's potential energy, and ended with 'value from kinetic energy calculations' instead of a number. | ||
| StudyFetch | Error | 0% |
| Why: The tester reported the app errored out on this problem; scored 0. | ||
| Turbo AI | Error | 0% |
| Why: The tester reported the app errored out on this problem; scored 0. | ||
| Solvely | 6.45 rad/s | 0% |
| Why: Wrong: turned the link about y (it turns about x, the fixed rod), so B moved along x, rod AB translated with the collar (v_A = −0.5ω instead of 0) and the collar got kinetic energy; 6.45 instead of 10.8 rad/s. | ||
| NotebookLM | 6.14 rad/s | 0% |
| Why: Wrong: misread the figure. Took link BC as 1.3 m long (the 1.3 m is rod AB) and C 0.5 m along y, so AB came out 1.84 m and the drop 1.3 m; 6.14 instead of 10.8 rad/s. | ||
Problem 9
Rod assembly on a ball-and-socket: angular velocity after an impulse
3D angular impulse and momentum
Textbook problem, listed by citation only: R.C. Hibbeler, Engineering Mechanics: Dynamics, 14th ed. (Pearson, 2016), Prob. 21–29, as printed. Key from the worked solution shared by the owner, checked by an independent vector solve.
| App | (a) ω, x component | (b) ω, y component | Score |
|---|---|---|---|
| Answer key | 8.727 rad/s ±1% | −122.2 rad/s ±1% | |
| Solvely | ω = 8.73 i − 122 j rad/s | (see part a) | 100% |
| ChatGPT | no final answer | no final answer | 100% |
| Claude | ω = 8.73 i − 122 j rad/s | (see part a) | 100% |
| MyStudySidekick | w = 8.7273 i − 122.182 j rad/s | (see part a) | 100% |
| Quizlet | No answer | No answer | 0% |
| Why: No answer: misread the assembly (AB and CD along y, D at (1, 0.5, 0)), set up the inertia tensor in symbols and stopped ('by evaluating the inertia properties, you will obtain…'). | |||
| Knowt | ω = −6 rad/s | (see part a) | 0% |
| Why: Wrong: treated the assembly as one 2 m rod about its end (J = mL²/3) and set the linear impulse (−8 N·s) equal to the angular momentum; a scalar −6 rad/s instead of 8.73 i − 122 j. | |||
| StudyFetch | Error | Error | 0% |
| Why: The tester reported the app errored out on this problem; scored 0. | |||
| Turbo AI | Error | Error | 0% |
| Why: The tester reported the app errored out on this problem; scored 0. | |||
| NotebookLM | ω = −13.8 i − 9.41 j − 2.86 k rad/s | (see part a) | 0% |
| Why: Wrong: invented the geometry. Gave the assembly a vertical segment GB along z and a 1 m arm BA, which the figure does not show (BC is 2 m along y through G, AB and CD 0.5 m along x); 8.73 i − 122 j is the key. | |||
Problem 10
Disk rolling on the ground around a vertical shaft: normal and friction force
3D kinetics (gyroscopic motion)
Textbook problem, listed by citation only: R.C. Hibbeler, Engineering Mechanics: Dynamics, 14th ed. (Pearson, 2016), Prob. 21–59, as printed. Key from the worked solution shared by the owner, checked by an independent vector solve.
| App | (a) normal force on the ground | (b) frictional force on the ground | Score |
|---|---|---|---|
| Answer key | 148.1 N ±1% | 0 N ±0.5 N | |
| Solvely | N = 148 N, F = 0 | (see part a) | 100% |
| Claude | N = 148 N, F = 0 | (see part a) | 100% |
| Quizlet | N = 598.1 N | F = 125 N | 0% |
| Why: Wrong: put the disk's centripetal acceleration (horizontal, toward the shaft) into the vertical force balance (N − mg = mΩ²r, adding 500 N), and balanced the gyroscopic moment with friction about the disk's centre instead of with the normal force about the pin B; corrected itself twice mid-solution ('Wait…', 'Correction:'). 598.1 N and 125 N instead of 148 N and 0. | |||
| Knowt | N = 98.1 N, F = 100 N | (see part a) | 0% |
| Why: Wrong: no gyroscopic moment; took N as the weight alone and invented a 'centripetal' friction of m·r·ω² using the disk's radius (0.4 m) as the path radius. | |||
| StudyFetch | Error | Error | 0% |
| Why: The tester reported the app errored out on this problem; scored 0. | |||
| Turbo AI | Error | Error | 0% |
| Why: The tester reported the app errored out on this problem; scored 0. | |||
| NotebookLM | N = 98.1 N, F = 50 N | (see part a) | 0% |
| Why: Wrong: misread the dimensions (disk radius 0.2 m, A on a 0.4 m circle; the figure gives 0.4 m and 2 m) and put the gyroscopic moment into friction instead of the normal force; N = 98.1 N (the weight alone) and F = 50 N instead of 148 N and 0. | |||
| ChatGPT | no final answer | no final answer | 0% |
| Why: Owner-reported: wrong. Response text not recorded. | |||
| MyStudySidekick | N = 98.1 N, F_f = 250 N | (see part a) | 0% |
| Why: Wrong: no gyroscopic moment in the normal force (N = weight alone) and the moment balance put into friction about the disk's axle; 98.1 N and 250 N instead of 148 N and 0. Went out flagged ('Check this setup… Confidence: medium'). | |||
Problem 11
Rocket struck by a meteoroid: axis of precession
torque-free motion
Textbook problem, listed by citation only: R.C. Hibbeler, Engineering Mechanics: Dynamics, 14th ed. (Pearson, 2016), Prob. 21–75, as printed. Key from the worked solution shared by the owner, checked by an independent vector solve.
| App | (a) direction angle α | (b) direction angle β | (c) direction angle γ | Score |
|---|---|---|---|---|
| Answer key | 90 deg ±1% | 9.12 deg ±1% | 80.88 deg ±1% | |
| Solvely | α 90°, β 9.12°, γ 80.9° | (see part a) | (see part a) | 100% |
| NotebookLM | α 90°, β 9.12°, γ 80.9° | (see part a) | (see part a) | 100% |
| ChatGPT | no final answer | no final answer | no final answer | 100% |
| Claude | α 90°, β 9.12°, γ 80.9° | (see part a) | (see part a) | 100% |
| MyStudySidekick | φx 90°, φy 9.1213°, φz 80.8787° | (see part a) | (see part a) | 100% |
| Quizlet | No answer | No answer | No answer | 0% |
| Why: No answer: put A on the y axis (it is on z, 3 m from G), so the impulse seemed to change only the spin; asked the student to confirm A's coordinates instead of answering. | ||||
| Knowt | axis of precession along the z axis | (see part a) | (see part a) | 0% |
| Why: Wrong: took A at 3 i (it is on z), added a vector to a scalar (144.69 + 900), and concluded the precession axis stays along z; also I_z = 2893.75 (miscomputed 4000 × 0.85²). | ||||
| StudyFetch | Error | Error | Error | 0% |
| Why: The tester reported the app errored out on this problem; scored 0. | ||||
| Turbo AI | Error | Error | Error | 0% |
| Why: The tester reported the app errored out on this problem; scored 0. | ||||