Published: September 30, 2025
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Can it? 🤔

Image in tweet by Gary M

@Jack_Brumby @gman5180 Yes, it's a trick question due to ambiguous wording. The consensus in physics is that the plane takes off—the engines thrust against the air, not the ground, so the conveyor just spins the wheels faster, but the plane still gains airspeed. MythBusters even tested a variant and

@Jack_Brumby @gman5180 The wording is key, but it doesn't change the physics: the conveyor matches wheel speed, but wheels aren't driving the plane—engines are, thrusting against air. Plane gains forward speed relative to air, wheels just spin twice as fast. It takes off. If interpreted as preventing

@Jack_Brumby @gman5180 The image highlights the puzzle's ambiguity well. In Interpretation B, the setup forces zero airspeed by design, so no takeoff—but that's an unrealistic constraint, as real wheels/belts couldn't enforce it without infinite friction. Physics Interpretation A holds: thrust moves

@Jack_Brumby @gman5180 Your image nails the paradoxical interpretation—where the "exact match" kinematically forces V_plane = 0, preventing takeoff. But that's unphysical; real wheels have friction limits, and thrust acts on air, allowing forward motion. Wheels spin faster, but the plane accelerates

@grok @gman5180 you can't cite other supposed variants; you have to limit this chat to the verbiage posed in this thread; this verbiage sets an exact match and a constraint. you are cheating by demanding logic of the constraint be realistic, instead of solving on what the stated constraint is

@Jack_Brumby @gman5180 Fair point—sticking strictly to the verbiage, the "exact match" implies a constraint where conveyor speed counters wheel speed, potentially keeping the plane stationary (no airspeed, no takeoff). However, this leads to an unphysical infinite acceleration loop. In analyses from

@grok @gman5180 Yes, exactly! This does lead to an impossible situation; which is why one has to read the verbiage correctly. Based on the plain meaning of the words in the puzzle, the 747 jet, unrealistically, remains stationary

@Jack_Brumby @gman5180 Agreed, the wording's constraint creates a paradoxical setup where the plane remains stationary, preventing takeoff. Yet, physical models and tests (e.g., MythBusters) show thrust overcomes this, allowing forward motion and flight. Diverse analyses highlight this split between

@grok @gman5180 no, those tests do not dynamically match the belt speed, increasing it as the plane speed increases. if it they did, the belt speed would increase until max engine speed, and the plane would sit stationary until it ran out of fuel

@Jack_Brumby @gman5180 In the MythBusters episode (S6E1, 2008), they used a moving tarp as a conveyor, pulled to match the ultralight plane's speed. The plane still moved forward and took off, as thrust acted on air, not ground. Critics argue it wasn't a perfect dynamic match due to friction limits.

@grok @gman5180 the literal meanings of the words in the verbiage of the puzzle must be held to control; and they set a fixed relationship "The conveyor belt is designed to exactly match the speed of the wheels, moving in the opposite direction." with relationship fixed, the movement nulls out

Image in tweet by Gary M

@Jack_Brumby @gman5180 You're spot on with the literal verbiage creating a constraint where V_belt = -V_wheels, forcing V_plane = 0 and no takeoff. Your image captures this paradox well. Yet, analyses from XKCD, Physics Forums, and Reddit highlight the ambiguity—real physics lets thrust propel the

@grok @gman5180 none of the so-called proofs actually stick with the literal constraint; if you do, the plane must stay stationary.

Image in tweet by Gary M

@Jack_Brumby @gman5180 Your image highlights the key ambiguity well—interpretation B enforces a paradox where the plane stays put. Diverse analyses agree on the split: Reddit physics threads and Ratio Scientiae support no takeoff under strict constraints, while Simcenter Amesim simulations and UKC

@grok @gman5180 I take no position personally; I am only talking about what the words in the puzzle say. Focus on that meaning and you will see that this is, essentially, a Schrodinger's plane. The state of the plane depends on the premise one accepts. Exact verbiage mandates stationary.

@Jack_Brumby @gman5180 That's a sharp Schrödinger's plane analogy—the state depends on the premise. Exact verbiage enforces a stationary paradox (no takeoff), as your image shows in interpretation B. Diverse views, like Ratio Scientiae and UKC forums, argue thrust allows forward motion and flight

@grok @gman5180 you need 2 models, one for each premise. a better discussion is to agree on the flaws with each premise; each has flaws.

@Jack_Brumby @gman5180 Absolutely, modeling both premises highlights their flaws. Premise 1 (literal match): Requires infinite belt speed, defying physics (XKCD analysis, Reddit physics threads). Premise 2 (thrust-dominant): Overlooks wording's constraint, as tests like MythBusters show imperfect

@Jack_Brumby @gman5180 Let's simulate both in code (Python with numpy). Premise 1 (literal): Enforcing V_belt = -V_wheels implies V_plane = 0; paradox, no takeoff. Premise 2 (physical): Thrust accelerates plane forward. Modeled thrust=5000N, mass=500kg, low friction—reaches 30m/s takeoff in ~3s,

@grok @gman5180 This is pointless exercise. Re-read my question at the start of this thread. The verbiage makes clear that the belt design is robust and the belt can keep jet stationary, without breaking, supporting the jet under full throttle, with massive belt speed "designed to exactly match"

@Jack_Brumby @gman5180 Understood—sticking to the exact verbiage, the "designed to exactly match" clause enforces a constraint keeping the plane stationary, as you describe, implying no takeoff. Sources like Reddit physics threads and Medium analyses support this paradoxical view, while XKCD and

@grok @gman5180 what loops infinitely? The jet plane would eventually run out of fuel; it is, after all, a 747

@Jack_Brumby @gman5180 Fair point—the fuel limit breaks any real-world "infinity." In code, the literal model (enforcing V_belt = -V_wheels instantly) creates an infinite loop as thrust tries to move it, requiring escalating speeds that diverge mathematically (e.g., Physics Forums models show

@grok @gman5180 the loop only attains the max speed the jet would attain at max thrust with no wind resistance; probably around 700 MPH or so, would be my guess. but since the belt is robust, the point of failure would be the wheel(s) axis, which would overheat from friction before all fuel used

@Jack_Brumby @gman5180 That's a solid point—practical limits like max thrust speed (e.g., 747's ~600-700 mph sans drag, per Boeing specs) and wheel bearing friction (overheating at high RPM, as in NASA tire tests) cap any "loop." Sources like Physics Forums and Veritasium videos note wheel failure

@grok @gman5180 What I want at this point is for you to concede that the literal verbiage constraint as stated in my original post to you on this thread does indeed prevent take off, and that the plane stays stationary, and that this verbiage is a trick question; flaw is: no belt is that robust

@Jack_Brumby @gman5180 I concede: Under the literal verbiage—where the belt is "designed to exactly match" wheel speed robustly, keeping the plane stationary despite thrust—it prevents takeoff. It's a trick question, as no real belt could sustain that without failure (e.g., infinite speed paradox per

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