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Could you help me sort out the physics behind this device.

It's controversial because it claims to be 'over unity'. I just want to understand the physics behind this.

Does the path taken by the ball before it is placed at the bottom of the ramp matter - if it is rolled down the ramp to the starting position or brought to the ramp from a distance, say 10 metres from the base of the ramp?

ANSWER: Hello Mr./Ms. given,

In the document that your link brings up, Donald E. Simanek does a good job of refuting the claims of free energy obtained from this. I refer you to the section towards the bottom of that document that has the heading "Where does the "excess" energy of the SMOT come from?" He uses an analogy to a commonly experienced situation. I will discuss that analogy in the next 3 paragraphs.

Call this case 1. A ball placed at the top of a ramp will roll down it when released, gaining speed. There is kinetic energy in that speed. You could ask for an explanation of that result as follows: where does that energy come from - it was just sitting at the top until released, it was not pushed down. The ball possessed potential energy when at the top of the ramp. That potential energy resulted from the position of the ball in a gravitational field. The ball gained kinetic energy as the potential energy decreased due to the decrease in elevation of the ball.

Call the smot case, case 2. So how does that case 1 analysis apply to the smot? In the smot, the ball starts at the bottom of a ramp, gravitationally speaking, so it does not start with gravitational potential energy. But magnetically a condition similar to case 1 exists. The ball has to be held back in the smot until you want the demonstration to start in the same way that the ball in case 1 has to be held back until you want the demonstration to start.

In case 1, the gravitational potential energy decreases as it gets closer to the object that it is attracted to: the earth. In case 2, a similar thing happens. Note that in both cases, the ball has to be held back until you want it released. That is an indication of the potential energy due to the attraction fields the ball experiences in the 2 cases. In case 1, the potential energy is due to a gravitational field; in case 2, the potential energy is due to attraction due to a magnetic field.

You asked if the choice of path of the ball matters when it is returned to the starting point. The answer is no. It depends on the difference in the forces the ball experiences at the 2 end points.

I hope this helps,

---------- FOLLOW-UP ----------

QUESTION: I have re-read the explanation given as well as other explanations of the device, and I have to agree that according to the laws of physics, the ball does not gain energy in the system described.

My follow-up question is this - if the track was level, and a series of angled magnets were set up as shown in this site:

Would there be any limit on the distance of the track - if enough magnets were available could the track extend for 100 metres or a kilometre for example?

Hello again,

The group of paragraphs at the end of the document titled "PERMANENT MAGNET GUNS" indicates problems encountered when the number of magnet pairs is increased. The document indicates suspected causes of those problems and suggests that they can be managed. If that is true on the large scale you are talking about, I don't see a reason that what you suggest could not be achieved.

I hope this helps,


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Steve Johnson


I would be delighted to help with questions up through the first year of college Physics. Particularly Electricity, Electronics and Newtonian Mechanics (motion, acceleration etc.). I decline questions on relativity and Atomic Physics. I also could discuss the Space Shuttle and space flight in general.


I have a BS in Physics and an MS in Electrical Engineering. I am retired now. My professional career was in Electrical Engineering with considerable time spent working with accelerometers, gyroscopes and flight dynamics (Physics related topics) while working on the Space Shuttle. I gave formal classroom lessons to technical co-workers periodically over a several year period.

BS Physics, North Dakota State University
MS Electrical Engineering, North Dakota State University

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