Sigh, I’m tire of you posting that stupid video: The vacuum-cleaner balloon car demo is flawed at every step. Here’s the full teardown:
1. It’s NOT a vacuum. Space is ~10^-12 Pa. A household vac creates only ~15-30 kPa suction (partial low pressure) strong airflow. Not empty space.
2. The hose is an ACTIVE external device (powered fan grounded to Earth). Real space vacuum has zero external machinery or ambient molecules.
3. Thrust formula proves it should work BETTER in low pressure: F = ṁv_e A_e(P_e - P_amb). Lower P_amb increases thrust. Yet the cart stops → external interference, not vacuum failure.
4. Suction drag overwhelms tiny balloon thrust. Straw A≈2.8e-5 m², ΔP_vac≈20 kPa → F_suction≈0.57 N backward. Balloon thrust ~0.2-0.4 N forward. Net drag stops it.
5. Violates momentum conservation. System (car balloon) is no longer isolated—the hose transfers momentum to the ground via its fan. In true vacuum, rocket exhaust is isolated → car accelerates.
6. Real tests destroy the myth: balloons & cold-gas rockets accelerate in actual vacuum chambers (Action Lab, NASA).
Thrust is higher in vacuum, exactly as physics predicts.
The demo doesn’t prove “rockets need air.” It proves bad experimental design motivated reasoning. Rockets push against their own exhaust mass via Newton’s 3rd law. Works (better) in space.
(End of debunk)