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38
votes
5answers
7k views

Freefall into snow

In the movie Frozen, the following dialogue takes place: Anna: "It's a hundred-foot drop." Kristoff: "It's two hundred." Anna: "Okay, what if we fall?" Kristoff: "There's 20 feet of ...
17
votes
4answers
5k views

Boiling water and salt

I would like to have a good understanding of what is happening when you add salt to boiling water. My understanding is that the boiling point will be higher, thus lengthening the process (obtaining ...
12
votes
2answers
423 views

Are there any inventions/applications in our world based on QFT?

Are there nowadays any actual devices or experimental applications which are based on the quantum field theory and if so, how are they related to QFT? I could not find any similar question besides ...
9
votes
5answers
3k views

Are there any practical applications of the uncertainty principle

I believe GPS works because of extremely small time differences between the satellites. Because of how small the time differences are, it needs to take into account gravity's effect on time. ...
8
votes
4answers
15k views

Practical applications for a Bose-Einstein condensate

What are the main practical applications that a Bose-Einstein condensate can have?
8
votes
2answers
929 views

Practical uses of antimatter in the present

I recently found out that a PET scan stands for a positron emission tomography. Are there any other practical uses of antimatter in the present?
8
votes
2answers
5k views

Do Microwave oven cook times grow linearly with Wattage? Calculating optimal cook time

So this is a completely random and trivial question that was prompted by looking at my microwave oven and the back of a TV dinner and my google searching failed to produce a meaningful answer so ...
8
votes
2answers
294 views

What is a capacitive screen sensing?

What should be a properties of a body so a contact with it can be detected by a capacitive touchscreen or a touchpad?
7
votes
0answers
106 views

Real world applications of post-1950s High Energy Physics [closed]

Imagine a world where people knew everything we know today except for high energy physics, where their knowledge ends at our ~1950s level. Is there any real world application, any particular piece of ...
6
votes
4answers
4k views

Are quantum mechanics calculations useful for engineering?

I heard it's is pretty tough to get results for more than a few quantum particles. Are quantum mechanical calculations useful at all for any technology that is being sold? Or do they use quasi-...
6
votes
2answers
5k views

How does the Kinect device work?

Some explanations of the device base it on a simple echo of light: "The camera transmits invisible near-infrared light and measures its “time of flight” after it reflects off the objects. Time-of-...
6
votes
2answers
241 views

Is it possible to estimate the speed of wind by the sound emitted by a cable of an overhead power line?

I was near ($\approx40m$) an overhead power line and I heard a sound coming from the cables of the power line; I think the sound was made by the vibrations of the power cables due to the wind but I am ...
5
votes
1answer
72 views

What causes the buzzing sound when the electricity changes into heat?

When I turn on any kind of electric heating (kettle, cooker, heater, ...), it keeps producing a constant buzzing sound. What is the exact cause of that sound? Do the electrons of the electric ...
5
votes
1answer
624 views

Can an induction coil heat two layers of metal?

Imagine we have an induction coil which is strong enough to heat a sheet of metal. We can put a sheet of ferromagnetic metal close to the coil at distance $h_1$, and it gets heated to temperature $t_1$...
4
votes
3answers
8k views

Cladding of optical fibers

Why do optical fibers usually have a cladding? Ok, if you put make a bundle of optical fibers this prevents that light leaks from one fiber to another fiber in contact. However, are there other ...
4
votes
3answers
6k views

If a vehicle is rolling down a hill, will its speed depend on the size of the wheel?

If I am sitting on a skateboard and travel downhill, will the velocity depend at all on the size of the wheel? The skateboard is only powered by gravity. There are a lot of variables to consider. ...
4
votes
2answers
511 views

Law for tap water temperature

I was wondering if anyone put together a law to describe the rising temperature of the water coming out of a tap. The setup is fairly simple: there's a water tank at temperature T, a metal tube of ...
4
votes
4answers
415 views

Applications of recoil principle in classical physics

Are there any interesting, important or (for the non physicist) astonishing examples where the recoil principle (as special case of conservation of linear momentum) is applied beside rockets and guns? ...
4
votes
7answers
2k views

How do I figure out the effects of wind on flight?

For a school project, I'm trying to make an automated flight planner, considering mainly the differences in flight paths according to wind. Now I've heard that flying with/against the wind affects ...
4
votes
3answers
660 views

Tire speed dependent friction

I have an old, non power steered car. When the car is stationary, the steering wheel is really tough to move, but as soon as I gain very little (0.5 kph or so) speed, the resistance is dramaticly ...
4
votes
0answers
200 views

Applications of quarks or string theory? [closed]

We wouldn't have computers if we didn't know about quantum physics. I understand understanding of general relativity is needed to make GPS work well. Has knowledge of quarks or string theory resulted ...
3
votes
3answers
4k views

Why should optical fibers be thin?

What are the reasons that optical fibers have to be thin (small radius of the fiber)? Is there a good picture which explains this in detail?
3
votes
2answers
260 views

Does the slip-stick phenomenon have any application?

The slip-stick phenomenon is present all around us, be it the noise of car breaks or in earthquakes. But does it have any real-life application?
3
votes
1answer
673 views

Phenomena which are incorrectly declared as resonance phenomena?

In standard college physics text books, high-school books and popular level physics books, the collapse of the Tacoma Narrows Bridge is often taken as an example of resonance. However a more detailed ...
3
votes
1answer
463 views

If layers of insulation are continuously added to a heated object, will it continue to be better insulated?

If you were to keep adding layers of insulation to something, like blankets to a person, would each blanket continue to improve the insulation? Or do you reach some point at which the next blanket ...
3
votes
2answers
458 views

What are the applications of delta function potentials?

Are there real applications for using delta function potentials in quantum mechanics (other than using it as an exactly solvable toy model in introductory undergraduate quantum mechanics textbooks) ?
3
votes
1answer
136 views

Applications of physics beyond QFT

Are there any applied results (inventions) based on physics beyond quantum field theory? By beyond QFT I mean any physical theory that is (maybe slightly) different from classical physics, relativity, ...
3
votes
2answers
2k views

Conservation of angular momentum in helicopter

I have a small RC-controlled toy helicopter with removable tail rotor. Suppose I remove the tail rotor, hold the tail with my hand, start the rotor until it moves with constant angular velocity and ...
3
votes
1answer
161 views

Containement system of a nuclear reactor: role of the water moderator

In a modern nuclear reactor for example a PWR there are multiple containment systems which prevent the release of radioactive material into the environment and shield the environment from the ...
3
votes
0answers
54 views

Energy dependence of integrating dosimeters

The graph shows the relative response of a dosimeter at different energies, normalized to 1.25 MeV Co-60 gamma rays. Curve A is the graph of the equation $$ \frac{\bigg(\frac{r}{X}\bigg)_\bar{E}}{\...
2
votes
8answers
4k views

Real world examples for projectile thrown upwards or downwards

I am preparing a physics course for high school about projectile motions. If a projectile moves with initial velocity $v_0$ in the gravitational field of the earth, the equation $$ s(t) = 1/2 g t^2 ...
2
votes
3answers
180 views

Controlling Neutrinos for Communication

Neutrinos travel straight through earth at the speed of light. Therefore, it seems that they could be great for intercontinental communication. Of course, I assume a lot still needs to be learned ...
2
votes
3answers
7k views

What are the applications of Gauss's law in technology? [closed]

Freshmen physics textbooks use Gauss's law plus symmetry to calculate the electric field. I was wondering if this method of finding the electric field using a symmetry is used in real applications in ...
2
votes
4answers
803 views

Are Lagrangians and Hamiltonians used by Engineers?

Analytical Mechanics (Lagrangian and Hamiltonian) are useful in Physics (e.g. in Quantum Mechanics) but are they also used in application, by engineers? For example, are they used in designing bridges ...
2
votes
2answers
2k views

Electrodynamics textbooks that emphasize applications

Please recommend undergraduate-level textbooks on electrodynamics which emphasize practical applications and real life examples. Please describe the book's level and contents and its intended audience ...
2
votes
1answer
163 views

What is the appropriate device for measuring energy loss from collision with surface?

The surface of a running track (i.e. cinder or rubber) has an effect on a runner's performance. I would like to get some device for measuring how much energy a runner loses on each surfaces. I've ...
2
votes
2answers
641 views

A man pulling himself up on a platform

Consider the following image: Is it possible that the man pulls himself up (suppose the weight of the platform is negligible), or just lift the right part of the platform up? How to analyse this ...
2
votes
1answer
211 views

Electric current streamlines in induction cooking vessel

I am looking for a plot of the typical streamlines of the electric induced currents ("eddy currents") in a induction cooking vessel. How can one theoretically predict the streamlines? How is it ...
2
votes
3answers
5k views

Do multiple permanent magnets aggregated together approach the same strength as a single magnet of the same size?

Here's an applied physics question. ;) If I buy some cube or sphere magnets like these, can I aggregate them together to create a stronger magnet (almost as strong as a single magnet)?
2
votes
2answers
828 views

Radar Frequency Bandwidth

I've come across an interesting question in the course of doing some exam review in a quantum mechanics book and thought I'd share it here. "What must be the frequency bandwidth of the detecting and ...
2
votes
0answers
116 views

Electron Beam Welding equation

I am studying for a nuclear physics course right now and came across a question and topic that sparked my interest - Electron Beam Welding. As I understand it, the process heats up the metal by ...
2
votes
0answers
46 views

What to work on? [closed]

(I am not exactly sure if this question is supposed to go here, but it seems like the appropriate place for it.) Hello Scientific Community, I am soon graduating from high school and, as everyone ...
2
votes
0answers
2k views

What are typical values of the critical thickness of insulation?

As most people who've had any elementary heat transfer course are aware, when insulating a pipe, wire, etc, there is a critical thickness for the insulation below which it causes greater heat transfer ...
2
votes
1answer
303 views

Additional accelerating force during take off of a rocket?

During the take off of a rocket, the exhaust produces some pressure below the rocket, which gives an additional force. How large is this force in comparison to the force produced directly by the ...
1
vote
2answers
198 views

What are the practical applications of quantum foundations?

Many quantum foundation researchers keep emphasizing that For All Practical Purposes (FAPP), quantum foundations are irrelevant. They even invented an acronym for it! Does that mean that quantum ...
1
vote
3answers
362 views

How can I measure the physical properties of a metallic string?

Metallic strings exist in different kinds but I would like to measure for a metallic string: the section/geometry along its length, to a precision of 1/100 mm its elongation when a tension is ...
1
vote
2answers
942 views

Is chaos theory essential in practical applications yet?

Do you know cases where chaos theory is actually applied to successfully predict essential results? Maybe some live identification of chaotic regimes, which causes new treatment of situations. I'd ...
1
vote
1answer
91 views

Examples of Riccati equations in physics [on hold]

I am looking for a Riccati equation $$y'(x)=a(x)+b(x)y(x)+c(x)y^2(x),$$ where $a(x),b(x)$ and $c(x)\neq 0$ in physics that is solvable (by easy methods). It would be great if at least one ...
1
vote
2answers
31 views

Projects to undertake Using Lasers [closed]

I need an economically feasible physics project that would use lasers in any manner preferably with respect to optics for a school projects class XII . Any suggestions are welcome no matter how crazy ...
1
vote
1answer
179 views

How can the transfer function of an infinite ladder network be used to solve real world problems?

In his lectures on Physics, Feynman illustrates a mathematical 'trick' in formulating the impedance of an infinite ladder, LC network. It basically counts on the assumption that adding one more 'rung' ...