Statics: how 9 AI study apps did on 14 college problems
Covers equilibrium of particles and rigid bodies, trusses, frames, friction, centroids, moments of inertia. Every app got the same problem text in a fresh chat, one attempt, no hints. Tested October 16, 2026.
| Rank | App | Accuracy | Problems graded |
|---|---|---|---|
| 1 | ChatGPT | 100.0% | 14 / 14 |
| 2 | MyStudySidekick | 100.0% | 14 / 14 |
| 3 | Solvely | 57.1% | 14 / 14 |
| 4 | Claude | 54.3% | 14 / 14 |
| 5 | NotebookLM | 36.9% | 14 / 14 |
| 6 | Quizlet | 19.3% | 14 / 14 |
| 7 | StudyFetch | 14.3% | 14 / 14 |
| 8 | Turbo AI | 7.1% | 14 / 14 |
| 9 | Knowt | 0.0% | 14 / 14 |
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. Greatest load on a ring held by three cables
- 2. Greatest crate mass on three rods
- 3. Maximum crate weight on three cables
- 4. Guyed antenna tower: turnbuckle cable and tower force
- 5. Sphere on a smooth parabolic surface held by a cable
- 6. Pipe assembly: equivalent force and couple at A
- 7. Parabolic distributed load on a shaft
- 8. Roller pulled over a step: given angle and minimum force
- 9. Bent rod on three journal bearings
- 10. Plane truss on a wall: force in every member
- 11. Loaded bridge truss: six members by sections
- 12. Wall crane: pin reactions and winch cable
- 13. Space truss on short links: three members at the loaded joint
- 14. Space truss on three ball-and-sockets: force in every member
Problem 1
Greatest load on a ring held by three cables
3D particle equilibrium
Textbook problem, listed by citation only: R.C. Hibbeler, Engineering Mechanics: Statics, 14th ed. (Pearson, 2016), ISBN 978-0-13-391542-6, Prob. 3–51 (figure Probs. 3–50/51), as printed. Back-of-book answer F = 1558 lb.
| App | (a) greatest force F | Score |
|---|---|---|
| Answer key | 1,558 lb ±1% | |
| ChatGPT | 1558.4 lb | 100% |
| Claude | 1558 lb | 100% |
| MyStudySidekick | 1558.44 lb | 100% |
| Quizlet | 873 lb | 0% |
| Why: Misread the figure: B(2,3,0), C(0,1,0), D(-3,2,0); its own equations then gave a negative cable force (T_AC = -2307 lb), it called that "impossible" and set T_AC = 800 lb anyway. Text copied with math broken one symbol per line. | ||
| Knowt | 1693 lb | 0% |
| Why: Put A at the origin and invented a planar geometry (B(3,0,0), C(0,0,-6), D(2,0,-1)); got a negative T_AD = -893 lb and added it as +893 lb. (Pasted unlabeled first, then again under "knowt"; identical text.) | ||
| StudyFetch | No answer | 0% |
| Why: No final answer. Misread the figure (B(5,0,0), C(-1,3,0), D(2,3,0)); its y-balance forced a negative tension, so it decided the figure must be different (C and D on opposite sides) and handed the system to Wolfram Alpha four times — twice with "but do not solve it yourself" in the query; Alpha read F as degrees Fahrenheit, Tb as tablespoons and Td as townsends. The reply ends there. | ||
| Turbo AI | Error | 0% |
| Why: Tester's report: Turbo's API errored out; no answer produced. Scored as a fail. | ||
| Solvely | 1030 lb (header) / 1818 lb (working) | 0% |
| Why: Headline says 1030 lb; the working ends at 1818 lb; neither is right. Misread C(-1,2,0) and D(2,3,0); assumed T_B = T_D = 800 lb "due to symmetry" without checking equilibrium. | ||
| NotebookLM | 1184 lb | 0% |
| Why: Misread C(-1,0,0) and D(1,2,0); skipped the x-balance consistency (3 equations, used y and x only to set ratios), AC governs at 800 lb. Reply cut off at the end when copied. | ||
Problem 2
Greatest crate mass on three rods
3D particle equilibrium
Textbook problem, listed by citation only: R.C. Hibbeler, Engineering Mechanics: Statics, 14th ed. (Pearson, 2016), ISBN 978-0-13-391542-6, Prob. 3–62, as printed. Back-of-book answer m = 88.5 kg.
| App | (a) greatest mass of the crate | Score |
|---|---|---|
| Answer key | 88.48 kg ±1% | |
| ChatGPT | 88.5 kg | 100% |
| MyStudySidekick | 88.4844 kg | 100% |
| Quizlet | 212 kg | 0% |
| Why: Misread the figure (A(3,0,1), B(0,2,2), C(0,-2,3)); its i-equation forces F_A = 0. Math copied one symbol per line. | ||
| Knowt | 458.1 kg | 0% |
| Why: Attribution inferred: pasted unlabeled right after "studyfetch failed"; formatting matches Knowt's labeled replies (blank bullet lines), and StudyFetch is recorded as no answer per the tester. Invented rod lengths of 2 m each, set all three rods to 1500 N and added them: m = 4500/9.81. | ||
| StudyFetch | No answer | 0% |
| Why: Tester's report: StudyFetch failed; no answer produced. Scored as a fail. | ||
| Turbo AI | Error | 0% |
| Why: Tester's report: Turbo's API errored out; no answer produced. Scored as a fail. | ||
| Solvely | 130 kg | 0% |
| Why: Misread C as (-2,3,3), which makes F_B = 0; OC governs at 1279 N. | ||
| NotebookLM | 181.6 kg | 0% |
| Why: Misread every point: A(3,-2,1), B(-2,-1,2), C(-2,3,3). Its stated rod forces (F_A = 1367.5 N, F_B = 685.3 N at the limit) are the correct-geometry values, not its own. | ||
| Claude | 130 kg | 0% |
| Why: Misread C as (-2,3,3) (the same misreading as Solvely), so F_B = 0 and m = 130 kg. | ||
Problem 3
Maximum crate weight on three cables
3D particle equilibrium
Textbook problem, listed by citation only: R.C. Hibbeler, Engineering Mechanics: Statics, 14th ed. (Pearson, 2016), ISBN 978-0-13-391542-6, Prob. 3–67, as printed. Back-of-book answer W = 375 lb.
| App | (a) maximum crate weight | Score |
|---|---|---|
| Answer key | 375 lb ±1% | |
| Solvely | 375 lb | 100% |
| ChatGPT | 375 lb | 100% |
| MyStudySidekick | 375 lb | 100% |
| Quizlet | 450 lb | 0% |
| Why: Misread B(1,2,2) and C(-2,1,1); got a negative cable tension, noted it was impossible, then asserted W = 450 lb without solving. Math copied one symbol per line. | ||
| Knowt | 662.5 lb | 0% |
| Why: Invented coordinates (B(2,2,2), C(0,2,1), D(0,0,-3)); set all tensions to 450 lb and summed a mix of y and z components. | ||
| StudyFetch | No answer | 0% |
| Why: Tester's report: StudyFetch failed; no answer produced. Scored as a fail. | ||
| Turbo AI | Error | 0% |
| Why: Tester's report: Turbo's API errored out; no answer produced. Scored as a fail. | ||
| NotebookLM | 450 lb | 0% |
| Why: Misread B as (-1,2,2) (x and y swapped), which makes all three tensions equal W. | ||
| Claude | 450 lb | 0% |
| Why: Misread B as (-1,2,2), the same misreading as NotebookLM, so all three tensions equal W. | ||
Problem 4
Guyed antenna tower: turnbuckle cable and tower force
3D particle equilibrium
Textbook problem, listed by citation only: R.C. Hibbeler, Engineering Mechanics: Statics, 14th ed. (Pearson, 2016), ISBN 978-0-13-391542-6, Prob. 3–65, as printed. Back-of-book answer F = 1.61 kip, F_AE = 2.91 kip.
| App | (a) maximum tension in cable AD | (b) force along the antenna tower at A | Score |
|---|---|---|---|
| Answer key | 1,610 lb ±1% | 2,914 lb ±1% | |
| ChatGPT | 1609.52 lb | 2914.28 lb | 100% |
| MyStudySidekick | 1609.52 lb | 2914.29 lb | 100% |
| Quizlet | 1760 lb | 3288 lb | 0% |
| Why: Misread every anchor (B(-10,15,0), C(10,12.5,0), D(0,-15,0)). Opening of the reply missing when copied ("tower."). Math copied one symbol per line. | |||
| Knowt | No answer | No answer | 0% |
| Why: No numbers: it sets up angles in words and ends "please finalize detailed values and finish out polynomial methods for exact numbers". Misread the geometry (D(12.5,15,0), cable heights 10 ft). | |||
| StudyFetch | No answer | No answer | 0% |
| Why: No final answer. Misread B(15,-10,0), C(0,-10,0), D(-10,15,0); Wolfram Alpha could not parse the system; a second query summed z-components to 2846 lb, and the reply ends on Wolfram output without stating T_AD or the tower force. | |||
| Turbo AI | Error | Error | 0% |
| Why: Tester's report (2026-10-16): Turbo's API is erroring out; no answer produced. Scored as a fail. | |||
| Solvely | 1670 lb (headline) / 1239 lb (working) | 1980 lb (headline) / 2619 lb (working) | 0% |
| Why: Headline and working disagree, and both are wrong under either rule. Misread B(15,-12.5,0), C(-10,-10,0), D(0,15,0). | |||
| NotebookLM | 984.8 lb | 1936.5 lb | 0% |
| Why: Misread C(-10,-15,0) and D(-12.5,15,0). | |||
| Claude | 503 lb | 1792 lb | 0% |
| Why: Misread C(-10,0,0) and D(12.5,15,0); AC governs in its model. | |||
Problem 5
Sphere on a smooth parabolic surface held by a cable
2D particle equilibrium
Textbook problem, listed by citation only: R.C. Hibbeler, Engineering Mechanics: Statics, 14th ed. (Pearson, 2016), ISBN 978-0-13-391542-6, Prob. 3–37, as printed. Back-of-book answer m_B = 3.58 kg, N = 19.7 N.
| App | (a) normal force on the surface | (b) mass of block B | Score |
|---|---|---|---|
| Answer key | 19.66 N ±1% | 3.584 kg ±1% | |
| Quizlet | 19.65 N | 3.58 kg | 100% |
| StudyFetch | 19.7 N | 3.58 kg | 100% |
| Turbo AI | 19.7 N | 3.59 kg | 100% |
| Solvely | 19.7 N | 3.58 kg | 100% |
| NotebookLM | 19.66 N | 3.58 kg | 100% |
| ChatGPT | 19.66 N | 3.58 kg | 100% |
| MyStudySidekick | 19.6553 N | 3.5842 kg | 100% |
| Knowt | 39.24 N | 2.55 kg | 0% |
| Why: Set N equal to the sphere weight and mixed cos(theta) and sin(60) terms in one "vertical" balance. | |||
| Claude | 40.7 N | 4.29 kg | 0% |
| Why: Took the 60 degree cable angle from the vertical instead of the horizontal; slope and normal direction right. | |||
Problem 6
Pipe assembly: equivalent force and couple at A
3D force system resultants
Textbook problem, listed by citation only: R.C. Hibbeler, Engineering Mechanics: Statics, 14th ed. (Pearson, 2016), ISBN 978-0-13-391542-6, Prob. 4–110, as printed. Back-of-book answer F_R = {44.5i + 53.1j − 40.0k} N, M_RA = {−5.39i + 13.1j + 11.4k} N·m.
| App | (a) resultant force F_R (vector; all three components within 0.6 N) | (b) couple moment at A, (M_R)_A (vector; all three components within 0.2 N·m) | Score |
|---|---|---|---|
| Answer key | {44.5336, 53.0731, −40.0000} N ±2% | {−5.3854, 13.0933, 11.3768} N·m ±2% | |
| Solvely | {44.5, 53.1, -40.0} N | {-5.39, 13.1, 11.4} N·m | 100% |
| ChatGPT | {44.53, 53.07, -40.00} N | {-5.39, 13.09, 11.38} N·m | 100% |
| Claude | {44.5, 53.1, -40.0} N | {-5.39, 13.1, 11.4} N·m | 100% |
| MyStudySidekick | {44.5336, 53.0731, -40} N | {-5.3854, 13.0933, 11.3768} N·m | 100% |
| Quizlet | {44.5, 53.1, -40.0} N | {-1.39, 17.1, 21.1} N·m | 50% |
| Why: Force right; position vector wrong (0.65, 0.3, -0.2): swapped the 400 and 300 mm runs. | |||
| Knowt | {53.0, 30.6, 51.4} N | {20560, -10280, -20788} N·m | 0% |
| Why: Wrong force direction (z positive, x/y swapped), wrong position vector, and mm not converted to m in the moment. | |||
| StudyFetch | No answer | No answer | 0% |
| Why: No answer: the reply is pages of second-guessing the pipe path ("Hmm" dozens of times), tries to recall a published answer ("my memory of the answer M_A = {-33.8i - 4.16j + 24.4k}"), and is cut off mid-sentence. | |||
| Turbo AI | {30.6, 25.7, -69.3} N | {-17.4, 25.9, 1.88} N·m | 0% |
| Why: Took the 30° from the vertical (not the horizontal) and the 40° from x; added a second 200 mm drop that is not there (r_z = -0.4). Both vectors wrong. | |||
| NotebookLM | {53.1, 44.5, -40.0} N | {-7.09, 11.39, 3.26} N·m | 0% |
| Why: Position right; measured the 40° from +x instead of +y, so F_x and F_y are swapped. | |||
Problem 7
Parabolic distributed load on a shaft
distributed loads
Textbook problem, listed by citation only: R.C. Hibbeler, Engineering Mechanics: Statics, 14th ed. (Pearson, 2016), ISBN 978-0-13-391542-6, Prob. 4–159, as printed. Back-of-book answer d = 2.22 ft.
| App | (a) magnitude of the resultant force | (b) location from A | Score |
|---|---|---|---|
| Answer key | 73.33 lb ±1% | 2.216 ft ±1% | |
| Solvely | 73.3 lb | 2.22 ft | 100% |
| NotebookLM | 73.33 lb | 2.22 ft | 100% |
| ChatGPT | 73.67 lb | 2.208 ft | 100% |
| Claude | 73.3 lb | 2.22 ft | 100% |
| MyStudySidekick | 73.33 lb | 2.22 ft | 100% |
| Quizlet | 72.333 lb | 2.32 ft | 0% |
| Why: Split the load into a straight line, the parabola and another straight line instead of one parabola over the whole shaft. | |||
| Knowt | 84.33 lb | 2.35 ft | 0% |
| Why: Treated the end sections as uniform 28 and 18 lb/ft loads; placed centroids at segment midpoints. | |||
| StudyFetch | No answer | No answer | 0% |
| Why: Tester's report: failed, no answer produced. Scored as a fail. | |||
| Turbo AI | No answer | No answer | 0% |
| Why: Tester's report: failed, no answer produced. Scored as a fail. | |||
Problem 8
Roller pulled over a step: given angle and minimum force
2D rigid-body equilibrium
Textbook problem, listed by citation only: R.C. Hibbeler, Engineering Mechanics: Statics, 14th ed. (Pearson, 2016), ISBN 978-0-13-391542-6, Probs. 5–29 and 5–30 (one figure), as printed. Back-of-book answers 5–29 P = 272 N; 5–30 P_min = 271 N.
| App | (a) 5–29: P at θ = 30° | (b) 5–30: minimum P | (c) 5–30: direction θ of the minimum P | Score |
|---|---|---|---|---|
| Answer key | 271.7 N ±1% | 271.1 N ±1% | 33.56 ±0.5 | |
| Quizlet | 271.6 N | 271.0 N | 33.55 | 100% |
| StudyFetch | 272 N | 271 N | 33.6 | 100% |
| Solvely | 272 N | 271 N | 33.6 | 100% |
| NotebookLM | 271.7 N | 271.1 N | 33.6 | 100% |
| ChatGPT | 271.66 N | 271.13 N | 33.56 | 100% |
| Claude | 272 N | 271 N | 33.6 | 100% |
| MyStudySidekick | 271.657 N | 271.134 N | 33.5573 | 100% |
| Knowt | 817.5 N | no final answer | no final answer | 0% |
| Why: 5-29: moment arms wrong (W arm taken as 0.25 m, P arm as 0.3 sin 30°). 5-30: no answer ("90°, 60 for efficacy"). | ||||
| Turbo AI | No answer | No answer | No answer | 0% |
| Why: The tester reported the app could not solve it (no usable answer); scored 0. Reply text not saved. | ||||
Problem 9
Bent rod on three journal bearings
3D rigid-body equilibrium
Textbook problem, listed by citation only: R.C. Hibbeler, Engineering Mechanics: Statics, 14th ed. (Pearson, 2016), ISBN 978-0-13-391542-6, Prob. 5–73, as printed. Back-of-book answer C_y = 800 N, B_z = 107 N, B_y = 600 N, C_x = 53.6 N, A_x = 400 N, A_z = 800 N.
| App | (a) |A_x| (magnitude; sign depends on the assumed sense, graded by hand for a consistent frame) | (b) |A_z| (magnitude; sign depends on the assumed sense, graded by hand for a consistent frame) | (c) |B_y| (magnitude; sign depends on the assumed sense, graded by hand for a consistent frame) | (d) |B_z| (magnitude; sign depends on the assumed sense, graded by hand for a consistent frame) | (e) |C_x| (magnitude; sign depends on the assumed sense, graded by hand for a consistent frame) | (f) |C_y| (magnitude; sign depends on the assumed sense, graded by hand for a consistent frame) | Score |
|---|---|---|---|---|---|---|---|
| Answer key | 400 N ±1% | 800 N ±1% | 600 N ±1% | 107.2 N ±1% | 53.59 N ±1% | 800 N ±1% | |
| ChatGPT | -400 N | 800 N | 600 N | -107.18 N | 53.59 N | -800 N | 100% |
| MyStudySidekick | -400 N | 800 N | 600 N | -107.18 N | 53.5898 N | -800 N | 100% |
| Quizlet | A_y = -346.4 N | A_z = -150 N | B_x = -300 N | B_z = 86.6 N | C_x = 150 N | C_y = -43.3 N | 0% |
| Why: Misread the frame (A on -x, B on +y; the legs run along -y and -x) and the force: F = (600, 346.4, -400) N, with the 60° taken from the vertical (key: (346.4, 200, -692.8)). Moment equations then not consistent with its own setup; every component wrong. Copy repeated each formula as rendered and source text; kept once. | |||||||
| Knowt | No answer | No answer | No answer | No answer | No answer | No answer | 0% |
| Why: No numbers: resolves F wrongly (F_z = +692.8, up), puts A at the origin, writes only force sums, and ends without solving ("we would commonly substitute known reaction forces..."). | |||||||
| StudyFetch | No answer | No answer | No answer | No answer | No answer | No answer | 0% |
| Why: No answer: four Wolfram|Alpha calls, three of which failed to parse its equation systems; it computed only 800 cos 60° and 800 sin 60° and stopped without any reactions. | |||||||
| Turbo AI | A_x = -115 N | A_z = 364 N | B_x = -231 N | B_z = 329 N | C_x = 0 | C_y = -200 N | 0% |
| Why: Force vector right (346.4, 200, -692.8) N, but the frame is wrong: put A and B both on the y-axis (B is on the other leg, along x), so the bearing directions and every reaction are wrong. | |||||||
| Solvely | A_y = -254 N | A_z = -214 N | B_x = -132 N | B_z = 907 N | C_x = -214 N | C_y = 454 N | 0% |
| Why: Same misreading as Claude (A on +x, B on +y); identical wrong numbers. | |||||||
| NotebookLM | A_y = 946.4 N | A_z = 2985.6 N | B_x = -3332.1 N | B_z = -2292.8 N | C_x = 2985.6 N | C_y = -1146.4 N | 0% |
| Why: Force vector right (346.41, 200, -692.82) N and its algebra is consistent, but the frame is wrong: A put at +2i and B at +1j (the legs run along -y and -x), so every reaction is wrong. | |||||||
| Claude | A_y = -254 N | A_z = -214 N | B_x = -132 N | B_z = 907 N | C_x = -214 N | C_y = 454 N | 0% |
| Why: Misread the isometric axes: put A on +x and B on +y (the legs run along -y and -x), so every component is wrong. | |||||||
Problem 10
Plane truss on a wall: force in every member
trusses (method of joints)
Textbook problem, listed by citation only: R.C. Hibbeler, Engineering Mechanics: Statics, 14th ed. (Pearson, 2016), ISBN 978-0-13-391542-6, Prob. 6–3, as printed. Back-of-book answer F_AC = 150 lb (C), F_AB = 140 lb (T), F_BD = 140 lb (T), F_BC = 0, F_CD = 150 lb (T), F_CE = 180 lb (C), F_DE = 120 lb (C), F_DF = 230 lb (T), F_EF = 300 lb (C).
| App | (a) F_AB (T +) | (b) F_AC (T +) | (c) F_BC | (d) F_BD (T +) | (e) F_CD (T +) | (f) F_CE (T +) | (g) F_DE (T +) | (h) F_DF (T +) | (i) F_EF (T +) | Score |
|---|---|---|---|---|---|---|---|---|---|---|
| Answer key | 140 lb ±1% | −150 lb ±1% | 0 lb ±0% | 140 lb ±1% | 150 lb ±1% | −180 lb ±1% | −120 lb ±1% | 230 lb ±1% | −300 lb ±1% | |
| Solvely | 140 lb (T) | 150 lb (C) | 0 | 140 lb (T) | 150 lb (T) | 180 lb (C) | 120 lb (C) | 230 lb (T) | 300 lb (C) | 100% |
| NotebookLM | 140 lb (T) | 150 lb (C) | 0 | 140 lb (T) | 150 lb (T) | 180 lb (C) | 120 lb (C) | 230 lb (T) | 300 lb (C) | 100% |
| ChatGPT | 140 lb (T) | 150 lb (C) | 0 | 140 lb (T) | 150 lb (T) | 180 lb (C) | 120 lb (C) | 230 lb (T) | 300 lb (C) | 100% |
| Claude | 140 lb (T) | 150 lb (C) | 0 | 140 lb (T) | 150 lb (T) | 180 lb (C) | 120 lb (C) | 230 lb (T) | 300 lb (C) | 100% |
| MyStudySidekick | 140 lb (T) | 150 lb (C) | 0 | 140 lb (T) | 150 lb (T) | 180 lb (C) | 120 lb (C) | 230 lb (T) | 300 lb (C) | 100% |
| Quizlet | 40 lb (C) | 150 lb (T) | 120 lb (T) | 40 lb (C) | 90 lb (T) | 0 | 426.7 lb (C) | 383.4 lb (T) | no final answer | 0% |
| Why: Wrong from the first joint: took ΣF_y at A as +0.8F_AC − 120 (AC in tension), then wrong reactions (moment arm 9 ft for the load at A about F, E_y = 426.7). EF never given. Only AC magnitude matches, with the wrong sense. | ||||||||||
| Knowt | No answer | No answer | No answer | No answer | No answer | No answer | No answer | No answer | No answer | 0% |
| Why: The tester reported the app could not solve it (no usable answer); scored 0. Reply text not saved. | ||||||||||
| StudyFetch | No answer | No answer | No answer | No answer | No answer | No answer | No answer | No answer | No answer | 0% |
| Why: The tester reported the app could not solve it (no usable answer); scored 0. Reply text not saved. | ||||||||||
| Turbo AI | No answer | No answer | No answer | No answer | No answer | No answer | No answer | No answer | No answer | 0% |
| Why: The tester reported the app could not solve it (no usable answer); scored 0. Reply text not saved. | ||||||||||
Problem 11
Loaded bridge truss: six members by sections
trusses (method of sections)
Textbook problem, listed by citation only: R.C. Hibbeler, Engineering Mechanics: Statics, 14th ed. (Pearson, 2016), ISBN 978-0-13-391542-6, Probs. 6–29 and 6–30 (one figure), as printed. Back-of-book answers 6–29 F_HG = 1125 lb (T), F_DE = 3375 lb (C), F_EH = 3750 lb (T); 6–30 F_CD = 3375 lb (C), F_HI = 6750 lb (T), F_CH = 5625 lb (C).
| App | (a) 6–29: F_HG (T +) | (b) 6–29: F_HE (T +) | (c) 6–29: F_DE (T +) | (d) 6–30: F_CD (T +) | (e) 6–30: F_HI (T +) | (f) 6–30: F_CH (T +) | Score |
|---|---|---|---|---|---|---|---|
| Answer key | 1,125 lb ±1% | 3,750 lb ±1% | −3,375 lb ±1% | −3,375 lb ±1% | 6,750 lb ±1% | −5,625 lb ±1% | |
| Solvely | 1125 lb (T) | 3750 lb (T) | 3375 lb (C) | 3375 lb (C) | 6750 lb (T) | 5625 lb (C) | 100% |
| ChatGPT | 1125 lb (T) | 3750 lb (T) | 3375 lb (C) | 3375 lb (C) | 6750 lb (T) | 5625 lb (C) | 100% |
| Claude | 1125 lb (T) | 3750 lb (T) | 3375 lb (C) | 3375 lb (C) | 6750 lb (T) | 5625 lb (C) | 100% |
| MyStudySidekick | 1125 lb (T) | 3750 lb (T) | 3375 lb (C) | 3375 lb (C) | 6750 lb (T) | 5625 lb (C) | 100% |
| Quizlet | 5625 lb (C) | 3750 lb (C) | 3375 lb (T) | 3375 lb (T) | 6750 lb (C) | 5625 lb (T) | 0% |
| Why: Moment equations right in size but every tension/compression sense reversed (sign convention lost), and HG taken from a wrong ΣF_x (5625 C). HE, DE, CD, HI, CH have the right magnitudes but the wrong sense; nothing graded right. | |||||||
| Knowt | No answer | No answer | No answer | No answer | No answer | No answer | 0% |
| Why: No numbers: wrong joint (load "at H"), invented 30°/60° angles, and ended "this would require numerical substitution". | |||||||
| StudyFetch | No answer | No answer | No answer | No answer | No answer | No answer | 0% |
| Why: The tester reported the app could not solve it; scored 0. Reply text not saved. | |||||||
| Turbo AI | No answer | No answer | No answer | No answer | No answer | No answer | 0% |
| Why: The tester reported the app could not solve it; scored 0. Reply text not saved. | |||||||
| NotebookLM | 4500 lb (C) | 750 lb (T) | 4500 lb (T) | 5625 lb (T) | 4500 lb (C) | 937.5 lb (T) | 0% |
| Why: Wrong supports (simply supported span instead of the wall), so every force is wrong. Reply text summarised, not verbatim. | |||||||
Problem 12
Wall crane: pin reactions and winch cable
frames and machines
Textbook problem, listed by citation only: R.C. Hibbeler, Engineering Mechanics: Statics, 14th ed. (Pearson, 2016), ISBN 978-0-13-391542-6, Probs. 6–74/75 (one figure), as printed. Back-of-book answer 6–74 T = 350 lb, A_y = 700 lb, A_x = 1.88 kip, D_x = 1.70 kip, D_y = 1.70 kip.
| App | (a) 6–74: cable force T at the winch | (b) 6–74: A_x | (c) 6–74: A_y | (d) 6–74: D_x | (e) 6–74: D_y | Score |
|---|---|---|---|---|---|---|
| Answer key | 350 lb ±1% | 1,878 lb ±1% | 700 lb ±1% | 1,703 lb ±1% | 1,703 lb ±1% | |
| Solvely | 350 lb | 1.88 kip | 700 lb (down) | 1.70 kip | 1.70 kip | 100% |
| NotebookLM | 350 lb | 1878 lb | 700 lb (down) | 1703 lb | 1703 lb | 100% |
| ChatGPT | 350 lb | 1878 lb | 700 lb (down) | 1703 lb | 1703 lb | 100% |
| MyStudySidekick | 350 lb | 1878 lb | 700 lb (down) | 1703 lb | 1703 lb | 100% |
| Claude | 350 lb | 1.88 kip | 700 lb (down) | 1.58 kip (1575 lb) | 1.58 kip (1575 lb) | 60% |
| Why: Read the winch strand as 60° from the vertical (it is 60° below the horizontal), so the cable pull at B is (303.1, 175) instead of (175, 303.1): D_x = D_y = 1575 lb are wrong. A_x = 1878 comes out right by coincidence (1575 + 303.1), and A_y = 700 is unaffected. | ||||||
| Quizlet | 350 lb | no final answer | no final answer | no final answer | no final answer | 20% |
| Why: Solved only 6-75 (wrong: A_x 368, A_y 1326, D 1182) and said "for 6-74 simply set the weights to 0 and re-calculate" without doing it. Only the cable force (350 lb, same in both) is given for 6-74. | ||||||
| Knowt | No answer | No answer | No answer | No answer | No answer | 0% |
| Why: The tester reported the app could not solve it (no usable answer); scored 0. Reply text not saved. | ||||||
| StudyFetch | No answer | No answer | No answer | No answer | No answer | 0% |
| Why: The tester reported the app could not solve it (no usable answer); scored 0. Reply text not saved. | ||||||
| Turbo AI | No answer | No answer | No answer | No answer | No answer | 0% |
| Why: The tester reported the app could not solve it (no usable answer); scored 0. Reply text not saved. | ||||||
Problem 13
Space truss on short links: three members at the loaded joint
space trusses
Textbook problem, listed by citation only: R.C. Hibbeler, Engineering Mechanics: Statics, 14th ed. (Pearson, 2016), ISBN 978-0-13-391542-6, Prob. 6–55, as printed. Back-of-book answer F_DF = 5.31 kN (C), F_EF = 2.00 kN (T), F_AF = 0.691 kN (T).
| App | (a) F_EF (T +) | (b) F_AF (T +) | (c) F_DF (T +) | Score |
|---|---|---|---|---|
| Answer key | 2 kN ±1% | 0.6906 kN ±1% | −5.309 kN ±1% | |
| ChatGPT | 2.00 kN (T) | 0.691 kN (T) | 5.31 kN (C) | 100% |
| MyStudySidekick | 2.00 kN (T) | 0.691 kN (T) | 5.31 kN (C) | 100% |
| Quizlet | no final answer | no final answer | no final answer | 0% |
| Why: The tester reported this app got 6-55 wrong (0/3); the reply text was not saved. | ||||
| Knowt | no final answer | no final answer | no final answer | 0% |
| Why: The tester reported this app got 6-55 wrong (0/3); the reply text was not saved. | ||||
| StudyFetch | no final answer | no final answer | no final answer | 0% |
| Why: The tester reported this app got 6-55 wrong (0/3); the reply text was not saved. | ||||
| Turbo AI | no final answer | no final answer | no final answer | 0% |
| Why: The tester reported this app got 6-55 wrong (0/3); the reply text was not saved. | ||||
| Solvely | 1.53 kN (C) [headline: 2.00 kN (T)] | 4.24 kN (T) [headline: 4.00 kN (C)] | 7.83 kN (C) [headline: 5.00 kN (T)] | 0% |
| Why: Two contradictory answers: the headline says EF 2.00 T, AF 4.00 C, DF 5.00 T; the worked answer says EF 1.53 C, AF 4.24 T, DF 7.83 C. Geometry wrong (F straight above D at 3 m, loads swapped between x and y), and it invents EF "by symmetry". Graded on the worked answer; the headline EF matches the key but is contradicted by the working. | ||||
| NotebookLM | 3.00 kN (T) | 4.31 kN (C) | 0.309 kN (C) | 0% |
| Why: Took F directly above the middle of AD with EF along y, and ignored CF; wrong geometry so all three wrong. | ||||
| Claude | no final answer | no final answer | no final answer | 0% |
| Why: The tester reported this app got 6-55 wrong (0/3); the reply text was not saved. | ||||
Problem 14
Space truss on three ball-and-sockets: force in every member
space trusses
Textbook problem, listed by citation only: R.C. Hibbeler, Engineering Mechanics: Statics, 14th ed. (Pearson, 2016), ISBN 978-0-13-391542-6, Probs. 6–59/60 (one figure), as printed. Back-of-book answer 6–59 F_AD = 686 N (T), F_BD = 0, F_CD = 615 N (C), F_BC = 229 N (T), F_AC = 343 N (T), F_EC = 457 N (C).
| App | (a) F_AC (T +) | (b) F_AD (T +) | (c) F_BC (T +) | (d) F_BD | (e) F_CD (T +) | (f) F_EC (T +) | Score |
|---|---|---|---|---|---|---|---|
| Answer key | 342.9 N ±1% | 685.7 N ±1% | 228.6 N ±1% | 0 N ±1 N | −615.4 N ±1% | −457.1 N ±1% | |
| ChatGPT | 342.86 N (T) | 685.71 N (T) | 228.57 N (T) | 0 | 615.45 N (C) | 457.14 N (C) | 100% |
| Claude | 342.86 N (T) | 685.71 N (T) | 228.57 N (T) | 0 | 615.45 N (C) | 457.14 N (C) | 100% |
| MyStudySidekick | 342.86 N (T) | 685.71 N (T) | 228.57 N (T) | 0 | 615.45 N (C) | 457.14 N (C) | 100% |
| NotebookLM | 0 | 0 | 0 | 0 | 0 | 800 N (T) | 17% |
| Why: Put the load at C instead of D and invented members (AB, AE, DE); everything zero except EC = 800 T. BD = 0 matches the key by accident. | |||||||
| Quizlet | 1083 N (T) | 1733 N (C) | 1083 N (C) | 1733 N (T) | 0 | no final answer | 0% |
| Why: Geometry invented (A(1,0,0), D(3.5,0.75,2), E at C); EC never solved. Nothing right. | |||||||
| Knowt | No answer | No answer | No answer | No answer | No answer | No answer | 0% |
| Why: The tester reported the app could not solve it (no usable answer); scored 0. Reply text not saved. | |||||||
| StudyFetch | No answer | No answer | No answer | No answer | No answer | No answer | 0% |
| Why: The tester reported the app could not solve it (no usable answer); scored 0. Reply text not saved. | |||||||
| Turbo AI | No answer | No answer | No answer | No answer | No answer | No answer | 0% |
| Why: The tester reported the app could not solve it (no usable answer); scored 0. Reply text not saved. | |||||||
| Solvely | 346 N (C) [headline 400 N (T)] | 490 N (T) [headline 566 N (C)] | 447 N (T) [headline 400 N (C)] | 345 N (T) [headline 566 N (C)] | 690 N (C) [headline 400 N (T)] | 800 N (C) [headline 400 N (C)] | 0% |
| Why: Headline and worked answer disagree on every member; both wrong. Coordinates wrong (A at (0,1,0), B at (3.5,6,0)); invented member AB. | |||||||