Can a beam attached to a vehicle with a magnet move the vehicle forward and thus function as free, perpetual propulsion, replacing petrol? No, that's not true: This would not work, as a mechanism such as the one shown in a video circulating on social media would defy the laws of physics.
The claim appeared in a video (archived here) on TikTok on February 4, 2024. It showed a toy car with a beam on top that allegedly moved forward because of the magnetic force between two magnets, one at the end of the beam and the other on the front of the car. The video's text overlay (translated from Czech to English by Lead Stories staff) read:
The gas station hates it. A funny engineer built a machine for eternal motion using a magnet.
This is what the post looked like on TikTok at the time of writing:
(Source: TikTok screenshot taken on Mon Feb 26 07:45:07 2024 UTC)
Lead Stories asked Jan Batysta (archived here), an engineer and doctoral student at the Solid State Physics Section of the Department of Semiconductors of the Institute of Physics of the Czech Academy of Science, about the claim. Batysta wrote in an email on February 23, 2024, that the video is "naturally a fraud," as Newton's third law of action and reaction tells us that for every force there is an equal force acting in the opposite direction. Batysta explained that just as the magnet acts on the car, the car acts on the magnet, so there is no reason why the car should move forward as the magnet would be attracted to the car by the same force, in the opposite direction. He added (as translated):
The truth is that there is no reason for the system to move in one direction or the other. If the magnet and the car are firmly connected, they cannot attract each other unless the mutual attraction is greater than the strength of the connection.
The phenomenon is explained further in a YouTube video on the account Integral Physics here on September 26, 2023. The video shows why such a mechanism would not work as free propulsion, with the example of a truck with a steel plate at the front and a magnet in front of it, mounted on a connecting beam. The magnet is going to pull forward on the truck but the beam is going to act backward on the truck, according to Newton's third law, meaning that the truck would not move.
