Category: wheels

What source of energy keeps the earth and the planets orbiting the sun or keeps electrons orbiting the nuclei of atoms? – AW

It takes no additional energy to keep those objects orbiting—the earth’s inertia keeps it moving around the sun. If the sun weren’t there, the earth would continue forward in a straight line at a steady pace forever because that is how free objects behave. It takes no energy or force to keep them moving. But the earth is drawn continuously inward by the sun’s gravity and so it travels in an elliptical arc instead of a straight line. Assuming that nothing adds or subtracts energy from the earth and sun, the earth will continue to orbit the sun forever. The same applies for the other planets and for electrons orbiting nuclei in an atom. In the latter case, it is electromagnetic forces that draw the electrons inward, rather than gravity.

Why is it impossible to make a wheel that turns forever, all by itself? — AWG, Karachi, Pakistan

While people are always trying to build perpetual motion machines, they will never succeed. All of these devices are intended to obtain useful energy—what physicists call “work”—from either nowhere or from less useful energy—what physicists often call “heat” or “thermal energy”. Obtaining work from nowhere is really impossible; energy is a conserved quantity, meaning that it simply cannot be created or destroyed. For a machine to do work, it must obtain energy from somewhere or something else. So if anyone tries to sell you a car engine that doesn’t take any fuel at all—thus creating work out of nowhere—don’t buy it! It’s a fraud.

As for machines that try to convert thermal energy completely into work, they are also impossible, but for a different reason. While they don’t violate the conservation of energy, they do violate the laws of thermodynamics. Thermal energy is disordered energy—it is energy that has been distributed randomly among the individual atoms and molecules in an object so that it cannot be easily reassembled to do useful work. When you burn a candle, all of the energy the candle once had is still in the room, but it’s much harder to use. Just as a coffee cup is much more useful before you drop it than after you drop it, so energy is much more useful before you disorder it than after you disorder it. The difficulty with reassembling thermal energy to do useful work is a statistical one: it’s unlikely that this energy will spontaneously reassemble itself in a useful manner, just as its unlikely that a dropped coffee cup will spontaneously reassemble itself in a useful manner. The laws of mechanics don’t prevent either of those reassemblies from occurring, but both reassemblies are statistically very unlikely to occur. How often have you dropped a broken cup and had it fall together rather than apart? So if someone tries to sell you a car engine that uses the thermal energy in the surrounding air as “fuel”—thus turning thermal energy completely into work—don’t buy it! It’s also a fraud.

A man falls into the center of the earth — how much does he weight? Which way is space bent in the center of the earth? — JW, Virginia Beach, VA

At the center of the earth, the man would be truly weightless and the space around him would be exactly flat (no curvature due to gravity). This special situation occurs because the gravitational effects of the earth around the man are perfectly balanced. With equal amounts of the earth’s mass on each side, there is no special direction in which the man would accelerate.

I just bought a set of nice chrome wheels with low profile tires for my car. Since these 4 wheels are 40 pounds heavier than the old ones, I removed 40 pounds of weight from the body of the car to compensate. My acceleration times and braking distances have increased dramatically. Why? — DTS, Shawnee, Kansas

When you accelerate forward from a stop, the car’s kinetic energy is increasing. The time it takes you to reach cruising speed is largely determined by how fast the car’s engine can increase the car’s kinetic energy. Stopping speed is similarly determined by how quickly the brakes can remove the car’s kinetic energy. While your car still has the same mass that it had before you changed wheels, and thus would seem to require the same transfers of energy to start and stop, that’s not the case. Transferring mass from the car’s body to its wheels has substantially increased the amount of kinetic energy the car has when it’s moving at cruising speed. That’s because each spinning wheel has two forms of kinetic energy. First, its center of mass is heading forward at cruising speed, so it has a translational (motion along a line) kinetic energy proportional to its mass. Second, it is spinning about its center of mass, so it has a rotational kinetic energy proportional to its moment of inertia (the rotational equivalent of mass). If most of each wheel’s mass is located near its periphery, its rotational kinetic energy will be roughly equal to its translational kinetic energy. The 40 pounds you transferred to the wheels is counting twice as much as before! You’ve effectively added 40 pounds to the mass of your car. Your new wheels and tires are demanding far more energy from your car’s engine and delivering far more energy to your car’s brakes than the old wheels did and you’ll have to remove an additional 40 pounds from the car’s body to compensate.

What are some everyday examples of friction? (For example, we couldn’t walk without friction.)

Before giving some examples, I’ll note that there are two different types of friction. First, there’s the static friction between two surfaces that are pressed together but are not sliding across one another. Second, there’s the sliding or dynamic friction between two surfaces that are moving across one another. Static friction allows objects to push one another sideways but doesn’t create thermal energy. Sliding friction also creates thermal energy (or heat).

Your example of walking is a case of static friction: your feet push backward on the sidewalk and the sidewalk reacts by pushing your feet (and you) forward. As further examples of static friction: holding a pencil, screwing in a light bulb, pulling a rope toward you hand over hand, pedaling a bicycle so that the ground pushes the wheel forward, keeping the dishes and silverware from blowing off a level picnic table on a windy day…

As examples of sliding friction: skidding the wheels of a automobile during a rapid start or stop, sliding down the pole in a fire station, skiing or skating, squeezing a bicycle’s caliper brakes against the wheel rims, shaping metal with a grinding wheel, sharpening a knife, sanding a wooden desktop…

I recently read a full-page ad for FREE ELECTRICITY from a company called United Services Company of America. Their Website is at http://UCSofA.com/Free%20Electricity.htm. I walked through their site and viewed some of their videos “demonstrating” clear violations of the well-known and well-founded Laws of Thermodynamics, and listened to the description of the new Fourth Law of Motion (following Newton’s other well known three). Are these people the same who were denied patent approval for a Perpetual Motion Machine? Have any reputable independent test labs reviewed their products under controlled conditions? Do they publish, even at a price, the fundamental mathematical and physical processes that allow for the claims that seem to be shown? I realize you’re not a “debunker”, but maybe you can shed some light on this. They have scheduled dozens of seminars across the country at considerable cost (and most likely considerable profit to them), and taken out full-page ads in national newspapers. The speakers do not comment on their academic training or experience, but tend to speak of hidden conspiracies from the power industry to stop their proliferation of free power. — DH

What a great find! This site is filled with pseudo-science at its best. I don’t know the history or training of these people, but it’s pure garbage. They use the words of science but without any meaningful content. Just as putting on a crown doesn’t make you a king, using phrases like “action and reaction” and “Newton’s third law” doesn’t mean that you are discussing real science.

I watched the video on the “Counter Rotation Device” and found the discussion of “Newton’s Fourth Law of Motion” quite amusing. The speaker claims that this fourth law was discovered about 30 years ago by a person now at their research lab. It is based on Newton’s third law, which the speaker simplifies to “for every action there is an equal and opposite reaction.” In a nutshell, his fourth law claims that you can take the reaction caused by a particular action and apply it to the action in the same direction—action causes reaction which causes more action which causes more reaction and so on. Pretty soon you have so much action and reaction that anything becomes possible. The video goes on to show devices that yield more power than they consume and that can easily become net sources of energy—by using part of the output energy from one of these energy multiplying devices to power that device, you can create endless energy from nothing at all.

Sadly enough, it’s all just nonsense. Newton’s third law is not as flexible as the speaker supposes and this endless feedback process in which reaction is used as action to produce more reaction is ridiculous. A more accurate version of Newton’s third law is: “Whenever one object pushes on a second object, the second object pushes back on the first object equally hard but in the opposite direction”. Thus when you push on the handle of a water pump, that handle pushes back on you with an equal but oppositely directed force. The speaker’s claim is that there is a way to use the handle’s push on you as part of your push on the handle so that, with your help, the handle essentially pushes itself through action and reaction. You can then pump water almost without effort. Sorry, this is just nonsense. It’s mostly just playing with the words action and reaction in their common language form: if you scare me, I react by jumping. That action and reaction has nothing to do with physics.

The speaker uses at least three clever techniques to make his claims more compelling and palatable. First, he refers frequently to a power-company conspiracy that is out to destroy his company and its products. Conspiracy theories are so popular these days that having a conspiracy against you makes you more believable. Second, he describes the fellow who discovered the fourth law of motion as a basement inventor who has taken on the rigid scientific establishment. Ordinary people love to see pompous, highly educated academics brought low by other ordinary people; it’s kind of a team spirit issue. And third, he makes casual use of technical looking equipment and jargon, as though he is completely at ease in the world of advanced technology. Movies have made it easier to trust characters like Doc Brown from “Back to the Future” than to trust real scientists.

In fact, there is no power-company conspiracy because there is no free electricity. The proof is in the pudding: if these guys really could make energy from nothing, they’d be doing it every day and making a fortune. They would be the power companies. If they were interested in public welfare rather than money, they’d have given their techniques away already. If they were interested in proving the scientific establishment wrong, they’d have accepted challenges by scientific organization and demonstrated their devices in controlled situations (where they can’t cheat). The fact is, they’re just frauds and of no more interest to the power companies than snake oil salespeople are to doctors. No decent people want to see others defrauded of money, property, or health, but the free electricity people present no real threat to the power companies.

The popular notion that an ordinary person is likely to upset established science is an unfortunate product of the anti-intellectual climate of our present world. Becoming a competent scientist is generally hard work and requires dedication, time, and an enormous amount of serious thinking. Physics is hard, even for most physicists. The laws governing the universe are slowly being exposed but it has taken very smart, very hardworking people almost half a millennium to get to the current state of understanding. Each new step requires enormous effort and a detailed understanding of a good part of the physics that is already known. Still, there is a common myth that some clever and lucky individual with essentially no training or knowledge of what has been discovered before will make some monumental breakthrough. The movies are filled with such events. Unfortunately, it won’t happen. In new or immature fields or subfields, it is possible for an essentially untrained or self-trained genius to jump in and discover something important. Galileo and Newton probably fit this category in physics and Galois and Ramanujan probably fit it in mathematics. But most of physics is now so mature that broad new discoveries are rare, and accessible only to those with extremely good understandings of what is already known. A basement tinkerer hasn’t got a prayer.

Finally, real scientists don’t always walk around in white lab coats looking serious, ridiculing the less educated, and trying to figure out how to trick the government into funding yet another silly, fraudulent, or unethical research project. In fact, most scientists wear practical clothes, have considerable humor, enjoy speaking with ordinary folk about their science, and conduct that science because they love and believe in it rather than as a means to some diabolic end. These scientists use the words of science in their conversations because it is the appropriate language for their work and there is meaning in each word and each sentence. The gibberish spoken by “scientists” in movies is often offensive to scientists in the same way that immigrant groups find it offensive when people mock their native languages.

I don’t know about any patent history for the free electricity organization but everyone should be aware that not all patented items actually do what they’re supposed to. In principle, the U.S. Patent Office only awards a patent when it determines that a concept has not been patented previously, is not already known, is not obvious, and is useful. The utility requirement should eliminate items that don’t actually work. One of my readers, a patent attorney, reports that he regularly invokes the utility regulation while escorting the “inventors” of impossible devices such as “free electricity” to the door. They consider him part of the conspiracy against them, but he is doing us all a service by keeping foolishness out of the patent system. However, proving that something doesn’t work often takes time and money, so sometimes nonfunctional items get patented. Thus a patent isn’t always a guarantee of efficacy. Patented nonsense is exactly that: nonsense.

Finally, how do I know that Free Electricity is really not possible? Couldn’t I have missed something somewhere in the details? No. The impossibility of this scheme is rooted in the very groundwork of physics; at the deepest level where there is no possibility of mistake. For the counter rotation device to generate 15 kilowatts of electricity out of nothing, it would have to be a net source of energy—the device would be creating energy from nothing. That process would violate the conservation of energy, whereby energy cannot be created or destroyed but can only be transferred from one object to another or converted from one form to another. Recognizing that our universe is relativistic (it obeys the laws of special relativity), the actual conserved quantity is mass/energy, but the concept is the same: you can’t make mass/energy from nothing.

The origin of this conservation law lies in a mathematical theorem noted first by C. G. J. Jacobi and fully developed by Emmy Noether, that each symmetry in the laws of physics gives rise to a conserved quantity. The fact that a translation in space—shifting yourself from one place to another—does not change the laws of physics gives rise to a conserved quantity: momentum. The fact that a rotation—changing the direction in which you are facing—does not change the laws of physics gives rise to another conserved quantity: angular momentum. And the fact that waiting a few minutes—changing the time at which you are—does not change the laws of physics gives rise to a third conserved quantity: energy. The conservation of energy is thus intimately connected with the fact that the laws of physics are the same today as they were yesterday and as they will be tomorrow.

Scientists have been looking for over a century for any changes in the laws of physics with translations and rotations in space and with movement through time, and have never found any evidence for such changes. Thus momentum, angular momentum, and energy are strictly conserved in our universe. For the counter rotation device to create energy from nothing, all of physics would have to be thrown in the trashcan. The upset would be almost as severe as discovering that 1+1 = 3. Furthermore, a universe in which physics was time-dependent and energy was not conserved would be a dangerous place. Free electricity devices would become the weapons of the future—bombs and missiles that released energy from nothing. Moreover, as the free electricity devices produced energy from nothing, the mass/energy of the earth would increase and thus its gravitational field would also increase. Eventually, the gravity would become strong enough to cause gravitational collapse and the earth would become a black hole. Fortunately, this is all just science fiction because free electricity isn’t real.

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About 18 months ago, I saw an episode on “Current Affairs,” in Australia, in which this dude made a “free electricity” machine, using magnets, fixed and non fixed-on a spinning wheel. While I know that I should be skeptical, I can’t help thinking “what if?” Have scientists carefully tested this stuff to see for sure that it does or does work? – P, Australia

Not surprisingly, no “free electricity” machines are ever released to real scientists for testing. That’s because the results of such testing are certain: those machines simply can’t work for very fundamental and incontrovertible reasons.

Like so many “scientific” conmen, the purveyors of this particular scam claim to be victims of a hostile scientific establishment, which refuses to accept their brilliant discoveries. They typically attack the deepest and most central tenets of science and claim that a conspiracy is perpetuating belief on those tenets. Their refusal to submit their work to scientific peer review is supposedly based on a fear that such review will be biased and subjective, controlled by the conspiracy.

The sad reality is that the “scientific establishment” is more than willing to examine the claims, but those claims won’t survive the process of inspection. In some cases, the authors of the claims are truly self-deluded and are guilty only of pride and ignorance. But in other cases, the authors are real conmen who are out to make a buck at public expense. They should be run out of town on a rail. >

Click here for more information about the “free electricity” hoax, sent in by readers of this site.

What exactly is the different between momentum and inertia?

Inertia is a concept—the property of an object to resist any change in its velocity. Momentum is a vector quantity—the product of an object’s mass times its velocity and an important characteristic of a moving object. Momentum is important because it’s conserved and it’s conserved in large part because of inertia and related concepts.

What’s going on with the wheels when a car accelerates?

As a car heads forward, its freely turning wheels begin to rotate. The torque that starts them rotating comes from static friction with the ground. The ground pushes backward on the bottoms of the wheels to keep them from sliding and this backward frictional force exerts a torque on the wheels. They begin to rotate so that their bottom surfaces head backward and their top surfaces head forward.

The car’s powered wheels turn for a different reason: they are driven by a torque from the car’s engine. As you step on the accelerator, the engine exerts a torque on the wheels and they begin to turn. They would skid backward across the ground where it not for static friction between the wheels and the ground. This static friction opposes the skidding by exerting a forward force on the bottom surface of the wheels. This static frictional force produces a torque on the wheels and that torque partly balances the torque from the engine. The wheels don’t skid and they’re angular velocities increase relatively slowly. However, the forward frictional force on the wheel’s bottom surface isn’t balanced elsewhere in the car and the car experiences a forward net force. The car accelerates forward.

Where does energy go when you try to push a heavy object and it doesn’t move? Thermal energy isn’t made, so why do people get tired?

While it’s true that there is no thermal energy made by static friction, since the object doesn’t slide, your body can still make thermal energy directly. You get tired because your muscles must turn useful food energy into thermal energy whenever they are under tension. If you are doing work, they also convert food energy into that work, but even when they aren’t doing work, they still convert food energy into thermal energy.