# All Questions

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### Perpetual Motion Machine 1: Magnetic Superconductor Loop Generating Energy with Piezoelectrics [closed]

I know there are a lot of perpetual motion machine designs out there, but I haven't found one that looks like this one. I will use this diagram. Assume the entire ring is made of a superconducting "...
59 views

### Potential, Kinetic, Thermal Energy?

When things move, potential energy turns into Kinetic energy, right? Then how does Kinetic energy convert to thermal energy?
9k views

### Why can't we make a perpetual motion machine by using a magnet to pull up a piece of metal, then letting it fall back down? [duplicate]

Obviously, a perpetuum mobile isn't possible by any law in physics, because energy can't be "created" or "destroyed", only transformed. This said, I've had an idea for a perpetuum mobile and can't ...
121 views

### Why friction causes energy to be lost in terms of heat when it appears to be an energy transfer mechanicsm?

For example, when we move/walk, we apply a force (via friction) on earth, and the earth in turn on us. So essentially I see it as an energy transfer as follows: Suppose I move in same direction as ...
35 views

### Dissipation of energy in inductors

Please explain the dissipation of energy in a circuit containing a resistance and inductor after the switched in the circuit is opened.I mean how do you explain that the energy that is across inductor ...
125 views

### Why do energy transfers always result some heat loss?

explain that energy transfers and transformations in mechanical systems always result in some heat loss to the environment. Like why is it necessary for a heat loss?
70 views

### Is the violation of time-reversal always associated with the violation of time-translation and vice-versa?

Is the violation of time-reversal symmetry always associated with the violation of time-translation symmetry? What about the converse? Is it possible for one to be violated while the other remaining ...
49 views

### Force, work and the apparent disappearance of Mechanical Energy [duplicate]

A man exerts force on a wall of bricks. The man must have consumed the energy he possessed (mechanical energy?) to exert the force. The man sweats and tires himself out but the wall does not move. ...
304 views

### Magnetic Turning Wheel [duplicate]

So a few years ago I came up with the idea of a magneticly powered wheel that could be attached to a generator and power it, it would not be infinite as over time magnets lose their power yet I think ...
43 views

### Potential gravitational energy versus potential spring energy [duplicate]

My textbook points out the following predicament, and I do not know the answer, despite a lot of thinking: A spring is hanging of a ceiling and a mass is attached. As a result the spring descends to ...
344 views

### Why is sound produced when we hit a metal? [duplicate]

We all know that metal are sonorous and produce sound on hitting but why is sound produced I thought that it might be a way of energy released on inelastic collision but then why not heat as heat is ...
120 views

### Is there a fundamental reason why “dynamic energy storage” is lossy?

Consider springs and moving masses - both can be used to store energy, the spring via tension $E=\frac{1}{2}kx^2$ and the mass via kinetic energy $E=\frac{1}{2}mv^2$. But day to day experience tells ...
1k views

### When is mechanical energy ever conserved for inelastic collisions?

So as I was taking a test today I encountered an intriguing question, the question came in two parts. The first parts, which I answered quite easily, was about whether or not mechanical energy is ...
183 views

### How to debunk this perpetual motion machine? [duplicate]

I know it's impossible. I normally find the flaw behind the principle, but this one is hard to crack. The two wheels are geared together, so that no magnet on one wheel "backlashes" the wheel in a way ...
67 views

### Is motion a form of energy?

I think I am running into a semantics difficulty. Loosely speaking when energy is converted from potential to kinetic is the motion a form of energy? Let us use an example: A ball drops to ...
63 views

### Can torsional force be used to harvest gravity?

I am curious if an idea I have will work or if it is the result of a lack of understanding of the physics involved. I am expecting to be disproved. Please excuse any lack of understanding on my part ...
291 views

### What is wrong with my perpetual motion machine model? [closed]

I know that perpetual motion machines are not possible and I want to know the reason why will this machine not work. The Car B has a magnetic bulge on top of it and Car B can only move forward. It ...
466 views

### Light traveling through different mediums

When light travels from air to another medium, why does the energy of the wave (photon) not change if the new medium is more resistive water, oil etc?
5k views

### What happens to the energy in an ocean wave after it breaks on a reef or the shore?

I understand that the conservation of energy essentially says that "energy can neither be destroyed or created but that it is transferred from one form to another." Given that, on the ocean, wind ...
41 views

### Rowing Oar - Loss of energy

Modern rowing oars for still water rowing are made of various carbon composites, during the drive phase of the stroke (force applied by the rower) the oars bend slightly as in the attached photo ...
1k views

### Where does kinetic energy go after a car crash?

More specifically, where does it go after it destroys the crumple zone? My assumption is that after a collision most of the kinetic energy will be transferred into the metal in the crumple zone (the ...
120 views

### Principle of energy conservation

I am new to physics and I hope you can help me solve this problem. When two objects collide with each other and stick, there is an internal force, so linear momentum is conserved. But when I ...
94 views

### What prevents this perpetual magnetic energy?

Understanding that questions similar have been asked, I wanted to propose a different one. Imagine you make a circle of 'permanent' magnets where each magnet has the N direction pointing inward at an ...
248 views

### Charge on a simple harmonic oscillator

Suppose we attach a charge on a simple harmonic oscillator. The oscillator should oscillate forever, but a charge attached would also lose energy so how would energy be conserved?
350 views

### Perpetual Motion Machines [closed]

If you go on YouTube, you will find a large number of machines that work for almost forever. But why do all of them stop working after some time? Which Law (Other than Conservation of Energy) ...
619 views

### Why is energy lost in EM waves? [closed]

I have read that accelerating charges lose energy through electromagnetic radiation. But no one explains the exact phenomena which takes place at atomic level. I understand why the accelerating ...
396 views

### Mechanical energy when ball is falling

I could not understand why mechanical energy of ball is not constant when time passes when a ball is falling in liquid with terminal velocity.
141 views

### Elastic or inelastic collision?

When two billiard balls collide in normal situation (on earth) we hear the sound due to their impact. This is a sufficient proof that the collision is inelastic in nature due to loss of energy in the ...
3k views

### Why does a rolling sphere stop?

I've just started studying Rotational Mechanics and one thing I'm confused about is that if friction is equal to zero when a body is rolling purely.. then why does a rolling body e.g. sphere.. stop ...
198 views

### Energy doesn't get lost? Basic understanding, please [duplicate]

If its true that energy isn't lost, its just transferred, where did the energy go from a falling object that hits the floor and stays there? It started with the most gravitational potential energy, a ...
2k views

### If string is stretched just by weight, where does the gravitational potential energy goes if only half is converted to elastic potential energy?

If a spring is stretched by a weight of mass m, (so the extension is $\Delta x$) then $k = \frac W{\Delta x} = \frac {mg}{\Delta x}$. So $k\Delta x= mg$. When the Spring is stretched by distance \$\...
583 views

### If I spinned a fan in a vacuum it will keep spinning forever. Why can we not make energy out of it? [duplicate]

Suppose we created a vacuum and spinned a turbine inside it with some amount of force. According to newton's second law it will keep spinning as there is no air resistance, so why can we not make ...
819 views

### Why does work done ultimately culminate as wasted heat?

Come to think of it, the work done on a body is converted into some form of energy.But why is it that it ultimately tends to produce heat? In physics we all talk about energy dissipation in the form ...
767 views

### Where does the energy go when engine braking?

If you're in gear in a car and not accelerating, the car slows down faster than it would from just air resistance and tire deformation. In normal braking, the energy is turned into heat from the brake ...
4k views

### Perpetual motion machine with magnets [duplicate]

I have been recently made aware of the following motor, which uses two magnets and a wheel to generate motion, and the creator of this machine claims that this motion is perpetual. Here is a YouTube ...
53 views

### Change of energy into friction?

If I am pushing a car and it does not move, I am doing no mechanical work. However, I am changing the energy that was stored in my cells into heat energy (maybe sound energy if my hand slips off the ...
398 views

### Why current loses its energy?

Can someone explain or give a link to explanation why current loses its energy? For example in simple circuit with lamp. I understand that the energy is spent for heating and lighting. But how exactly ...
91 views

### Do you know the principle which says that connecting two sources of similar kind produces a waste and destruction? [closed]

There is a great article, called commutation cells, which states that you cannot transfer kinetic energy from one container to another immediately, bypassing the potential energy storage. Otherwise, ...
18k views

### Can water be made to flow through a pipe using only gravity and resulting in a higher elevation at the end of the pipe from its starting point?

I am not a physics guy, so be nice to the layman, guys! Please note: not a homework type problem. This is a scenario being considered for real-world application. I have not yet considered details ...
2k views

### Temperature rise during friction

Why does the temperature increase when the load increases during friction? Why does the temperature increase when the contact time increases during friction?
6k views

### What happens to the kinetic energy of a dropped ball when it comes to rest on the ground?

If we want to drop a ball from a height, we calculated that potential energy at bottom is zero and we say it is converted into kinetic energy. At that movement, if it is a kind of sand, we find it ...
786 views

### Do transformers lose energy?

EDIT: The title should rather be how/why transformers lose energy My idea of a transformer is that it is composed of two separate wire windings around some metal core. The purpose is to increase/...
5k views

### What happens to half of the energy in a circuit with a capacitor?

For a simple circuit with a battery supplying a voltage V to a capacitor, let us assume that the charge on the capacitor is Q. Now, the work done by the battery or the energy supplied is given by the ...