In the picture above, there are three balls in separated small elevators. Elevator A lifts the ball upwards, elevator B stays still, elevator C moves the ball downwards, all in constant speed. (And this is a model, a simplification of the reality, we assume no...

Relation between sum of the forces and energy]]>

Need help drawing v-x graphs]]>

I don't understand something about torque. I can prove every definition about rotational motion if I assume that a point mass is moving in a circular motion.

and if I also define a point of rotation I dont need an object to rotate in order to have...

Torque: Point of choice]]>

What if the actual force for a newton was different?]]>

Brainstorm: Is absolute zero relative]]>

http://flip.it/AfcjP9 http://flip.it/AfcjP9

I am planning on building my first Focault Pendulum(As a physics projject for school) and I have a few questions. I am going to purchase a cable(it needs to be smooth and friction-less around 7 feet), I also am going to need to...

Foucault's Pendulum Recreation for Physics Project]]>

Conductive fluids and magnetism]]>

$$u = (\epsilon/2)E^2 + (\mu/2)H^2$$

One of the differences between the classical electromagnetic theory and the real world is that in classical EM all charge and current density, (ρ(

Correction to the field energy due to the existence of discrete charges]]>

On a (very) recent vacation, I took a cruise aboard the MSC Orchestra, almost 300 metres long and almost 100,000 tons.

During medium-high seas, I lay in my bunk (midship, near top deck, 120 feet up) and felt...

Resonance in large objects, say a cruise liner]]>

Consider an elastic sphere which is homogeneously charged and suferring an harmonic inflation and deflation.

Is it correct to explain the theoretical result that it does not emmit radiation, even though all of its charge elements are accelerating, as a systematic effect of destructive...

Why a pulsating charged sphere does not emit radiation?]]>

Assume desert 120F hot and very dry air can enter/exit at either bottom around ankles or at top around open...

Optimizing Evaporative Cooling via Sweat in Dry Desert?]]>

This device is fed by a broad-band source and the spectral response collected by an Optical Spectrum Analyzer is given....

How can I determine the length of a Multimode fiber?]]>

often considered to be "point particles", and I know there are

fundamental limits on measurements due to uncertainty in

position and momentum. I also know that according...

How could the "size" of a photon be measured?]]>

I have studied about heat transfer through conduction only in steady state but I wondered about this problem that I created.

Suppose you have a box that is insulated from all sides but Suppose a constant heat flow from that wall. Inside that box you have M kg of water at the same...

Heat transfer: transient state]]>

I know that the Welch–Satterthwaite equation exists, but that is for combining independent sample variances.

Is there an equivalent expression for dependent sample variances?

.

Example...

Degrees of freedom and dependent sample variances]]>

I was referring to this thread: https://www.physicsforums.com/threads/accelerating-atwoods-machine-problem.44305/ to solve a problem on accelerating atwood machines in which, naturally, one attempts to find the acceleration of each of the individual masses.

Although I now...

"Shifting" non-inertial frame in Accelerating Atwood Machine]]>

Simple cheap method of measuring mass distribution of object]]>

Please have a look on the attachment. Suppose that a 0.1 kg rubber ball having velocity of 60 m/s is moving between two walls A and B, and the distance between the walls is 1 m. It is having elastic collisions with the walls.

Let's focus on what is happening at wall B. The ball is moving...

Pressure exerted by an ideal gas]]>

I noticed that the reflection of light from the fingerprints on my iPhone screen depend on it's orientation toward a light source.

For instance, use your finger to make two perpendicular smudges accross the screen. You'll find that the...

Reflection from smartphone screen]]>

Solving Physics Problems]]>

Thanks in advance everyone.]]>

2. friction experienced by tyre at the road surface

compare with each other? are they some what equal ?.. I am interested in approximate ratio of the two values . Thx.]]>

What are the problems...

Freezer without refrigerant]]>

I am looking for a formula that describes the deflection of an inclined rope that is fixed in both ends, the left end is at the origin and the right end is at (xB, yB). The known parameters are; the length between the ends is L, the length of the rope is l, the initial angle is β and there...

Deflection of an inclined rope]]>

My guess is that cross-section...

Size of links and loads in the hydraulic system]]>

Tension (and Frequency) with Change in Temperature]]>

Changing distribution when going through a potential]]>

Calculating expected number of measurements]]>

Homebrewing a spectrometer]]>

I have a very simple doubt in the basics of radioactivity .

Nuclear fission is the splitting of the nucleus of a heavy atom such as U

Now my...

Simple doubt in nuclear fission]]>

But what is the L? And in what dimension?

Thanks heaps!]]>

I'm using my phone to take photos of assembly procedures on my electronics workbench. However, the focus...

Optical geometry of smartphone camera.]]>

Negative values for Gaussian Distribution]]>

If you were to use a subsea lifting bag filled with O2 it would rise to the surface.

Would the same happen with CO2? I assume the density of CO2 is different so the amount required would be more or less than O2, but it is still less dense than...

Does CO2 float?]]>

Can gravity be negative?]]>

This question has been bothering me for some time, so here it is.

I know that moving a charged particle, like an electron, generates a magnetic field. I know that moving electric charges in a circle (a loop of wire) generates a magnetic field. The question is, will a charge

Does a moving charge posess a generated magnetic field?]]>

1). Quantum theory forbids point particles, because points themselves do not make sense in phase...

The Problem with Point Particles]]>

I am having hard time to know if the finite angular displacement really a scalar quantity?

In some books they say angular displacement when finite is Scalar and when infinitesimal small is Vector, with direction perpendicular to plane of circle government by right hand rule.

I...

Controversy about the nature of finite angular displacement]]>

First of all I want to mention what believe or result of concepts, do I hold about rotational motion especially about the angular velocity. I assume that unlike velocity angular velocity has to worked out from some point. I will begin with particle for this I assume that the question...

Does a rotating rigid body has single angular velocity.]]>

Question about statistical mechanics]]>

2) What will happen to the...

Spring in space?]]>

The Nobel Prize in Physics is upcoming soon and I wanted to hear your opinions and expectations about some important discoveries or inventions which might end up receiving this most major prize in science. I look forward to hearing your thoughts!

Thanks.]]>

Please help]]>

Confusion with multiple impulses]]>

What would the weight of a column of water be at the center of the Earth?]]>

T-symmetry and WDWE with regards to a Universe from Nothing]]>

The symbol for electrical current is I. But so is rotational inertia! Are there any other symbols for rotational inertia/electrical...

Other symbols for rotational inertia?]]>

What does negative potential energy mean?]]>

I read that the mass of nucleons in nucleus of Oxygen-16 (or nucleus of another atom) is less than the sum of its nucleons if they were separated (also the mass of 8 protons and 8 neutrons).

But why does nucleons have less energy in nucleus of atoms than if they were separated? What causes...

What causes mass defect in the nucleus?]]>

In going from Newtonian gravity to General Relativity, we can do away with Newtonian gravity and use only General Relativity...

In the atom, we can...

Superceded Theories]]>

Warp jet?]]>

What Materials Absorb IR The Best?]]>

Electric field (in)dependent of distance?]]>

Electric field of a ring:integrate over dq or ds?]]>

Some students replied: The floating object is interacting with the water. Therefore it exerts a downward force on the water. The water then exerts an upward force on the object due to Newton's Third Law....

Is Newton's 3rd law sufficient to explain buoyancy force?]]>

Is it simply shining lights on material to see diffraction patterns? Why the word "Transform"? I can't get any definition of this in the net. Is it about performing Fourier Transform on the light and getting this displayed on the screen or does the screen...

Optical transforms]]>

I've been watching too much anime. I know that isn't the best way to ask a question scientific in nature, but visualizing bizarre situations is one of the best ways to come up with interesting questions.

Anyways, in order to break a rock by compressing it with your hands, you would need...

An infinitly dense human body]]>

I am trying to solve a problem where I want to know how many cylinders of N2 (50L, 200 bar) are needed to flush a pipe filled with oil.

The pipe diameter is 0.5", so the volume of the pipe is 0.133 m3 (with a length of 1050m) which is filled with oil.

Behind the N2 cylinders is a...

Amount of nitrogen needed to flush a pipe]]>

My question is : in this link, it states interesting situation in electrodynamics is one where the current density View attachment 209565 is...

Maxwell’s equations with varying charge but constant current]]>

$$S(U) = \sum_{i=1}^{\infty}a_iU^i = a_1 U + a_2 U^2 + \ ...$$ with ##a_i \in \mathbb{R}##.

What results could be obtained from such...

Analysis of the entropy S of an arbritary system can be written as a power series?]]>

I heard once that this could be done using one of the towers of the World Trade Center. So I assume one could also do this using the Sears / Willis Tower in...

How much would time pass between watching the sun set ...?]]>

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The probability that the system has the energy ε i.e.P(ε).

The system could have any energy between 0 and E.

So, P(ε) = 1/(no. of possible systems with different...

Canonical ensemble]]>

The wheel balances as a Segway by applying power to the wheel. (the classis reverse pendula).

However, since its a unicycle, it does not balance sideways, and I imagine that this colud be solved with a...

Making an electric unicycle really selfbalanced]]>

What's the physics description of "existence" ?]]>

Meaning of permeability in free space]]>

Thanks in advance.]]>

This is one of the factors to calc NPSH. Shows how much head is pushing liquid through the pump.

What does the specific gravity have to do with surface pressure of a liquid before it goes into the pump? Isn't it just involving the...

NPSH Suction Surface Pressure]]>

Joule Thompson effect]]>

Acceleration and gravity]]>

Magnetic field of a single charged particle]]>

I'm projecting a circular beam of some known divergence and power onto a surface angled relative to the center of the beam. Say holding a flashlight, with a cone of half angle

Irradiance distribution of projected beam]]>

I wonder why the energy that waves transfer is only dependent on amplitude?

E.g. in this animation:

http://lifecdn.dailyburn.com/life/wp-content/uploads/2015/02/2.Alternating-Slam4.gif

The waves on the rope transfer energy to the items on the right side.

Wouldn't there be...

Why the energy that waves transfer is only dependent on amplitude]]>

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I just have a general question about Guass's Law and the cylinders above. I don't really understand what the difference is between the 2 cylinders? They are both...

Conducting Cylinder vs Cylinder of Charge - Guass's Law]]>

Wave-matter interaction]]>

What properties allow me to see past Earth's curvature?]]>