This tag is for the classical concept of forces, i.e. the quantities causing an acceleration of a body. It expands to the strong/electroweak force only insofar as they act comparable to ‘classical’ forces. Use [tag:particle-physics] for decay channels due to forces and [tag:newtonian-mechanics] or ...

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79 views

What is the resolution of this Lewis-Tolman like paradox?

Though my question stands on its own, here is a brief overview of a well-explored question which I think might be helpful in finding the resolution to my question. The Lewis-Tolman Lever Paradox has ...
4
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163 views

Calculating Forces via Feynman diagrams?

How would one go about calculating forces that test objects feel using Feynman diagram methods? For example, say we have a massive object in GR so that the metric takes on the standard ...
3
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50 views

Centrifugal force in the two body problem?

In the two body problem, the Effective radial potential energy in general relativity is given by $$ V(r)=-\frac{G M m}{r}+\frac{L^{2}}{2\mu r^{2}}-\frac{G(M+m)L^{2}}{c^{2}\mu r^{3}} $$ where the ...
3
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0answers
28 views

Could a hydrophobic surface increase a liquid's resistance to compression/displacement?

Imagine a quantity of an aqueous (yet slightly viscous) solution is resting on a hydrophobic surface with a contact angle around 100°. A downward force is then applied as a (repellant) surface is ...
3
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66 views

Time evolution of symmetrical mechanical systems

I asked this previously in an earlier question, although admittedly my question was hard to find in the slew of info I provided there, so hopefully this will clarify things. Suppose there's a typical $...
3
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3k views

Forces and torques about the CENTER OF MASS of a physical pendulum

I'm currently stumped by the following situation. Say we've got a rectangular physical pendulum (think ruler with a hole-punch at one end). It's trivial to analyze the motion of the pendulum with the ...
2
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0answers
80 views

Deriving the formula for energy stored in a spring without using geometry (determining the area under a curve)?

Using Hooke's Law, we know that the force applied is proportional to the extension of the spring. Therefore by plotting a graph of force against extension, through the area under the curve we are able ...
2
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139 views

Lagrange: when a potential force, when a generalized force?

Consider the following case of a drum unrolling a mass that is on a massless string wrapped around the drum: According to my professor, here we must consider the mass $m$ being in a gravitational ...
2
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201 views

Lorentz force on superconductor vortices

I am reading a paper on superconductivity and in it it says that the vortices are subject to a Lorentz force given by $$\vec{F}_L=\frac{\Phi_0\vec{I} \times \vec{H}}{cH}$$ Here $\vec{F}_L$ is the ...
2
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0answers
35 views

What kind of forces would follow only the second part of shell theorem?

General expression of a force which would cancel out inside a uniform hollow shell. What about any closed surface?
2
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0answers
221 views

Odd experiment results (electromagnetics)

Okay, a bit of background. So I'm working on a linear accelerator (you might know it as a Gauss rifle), and I had worked through the equations I thought I needed (Magnetic force, displacement, etc.) ...
2
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0answers
193 views

Magnetic Force on a Ferromagenetic Material

I am currently working on a project involving solenoids, and I needed a force(Newtons, not a measure of magnetic field strength) equation. What I came up with after some digging around on the internet,...
2
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0answers
69 views

How is force felt at relativistic speeds?

Hypothetically, should a force feel the same as its measured force at relativistic speeds? Obviously a human body would not survive the force of a rotation at say, 0.6 the speed of light, but it’s ...
2
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622 views

Sum of energy in a free rotation with Algodoo software

I try to understand why Algodoo software (freeware) give an efficiency greater than unity. I tested several scenes and at each time I can look the software give energy, I don't say it's all the time ...
2
votes
0answers
183 views

Balloon tethering cable tension model (catenary tether)

If a moving balloon (let's say it's a blimp system with some rotors for movement) is connected to the ground by a cable that describes a catenary curve, how can we model the tension being applied on ...
2
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0answers
109 views

what forces are present when slicing an object.

I found here:What happens when we cut objects? that it is due to fracture wood splits open when using a wedge. Does it only apply when the wedge is already in the wood? How about the moment before a ...
2
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0answers
173 views

How do we derive force/acceleration vectors from Einstein's field equations?

I'm new here and I don't have any formal experience in physics beyond A-level. I've been exploring an idea for a space sim game someone else is developing in which propulsion of a spacecraft is ...
2
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0answers
95 views

Consistency of equation with special relativity?

The following is the equation which, I want to know, if it is valid in relativistic domain. Consider two equal charges moving in same direction with velocity $v$ and charge $q$ at a separation of $d$....
2
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371 views

What is wrong with this downforce calculcation?

I tried calculating the downforce of a spoiler I need for a robot. I used this formula. $$F = \frac{1}{2}Ac_a\rho v^2$$ Where $\rho$ is air density, $v$ is the speed of my robot, $c_a$ is the lift ...
2
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0answers
163 views

Robot controling pouring process from a bottle

I need to solve a problem within mechanic of fluids for a part of my thesis. Robot will pick up a bottle of beer, cola, julebrus or any other kind of beverage. And then it has to bring it to the glass ...
2
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0answers
212 views

Semiflexible discrete polymer chain

Suppose we have a 2D polymer model described by a set of 2D vectors {$\mathbf{t}_i$} ($i=1,2,\dots N$) of length $a$. The energy of the polymer is given by: $$ \mathcal{H}~=~-k\sum^N_{i=1}\mathbf{t}...
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0answers
44 views

Which fundamental force is behind friction?

In day to day life we come across situations where friction is used. What is the fundamental force behind friction. For eg. which is the force behind interlocked objects like nut and bolt, which is ...
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0answers
79 views

How do we know that electrons are affected by gravity?

There are some theories of gravity which explain it as emerging from other fundamental forces. To better understand the evidence for and against these theories, I would like to have a better ...
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0answers
61 views

Does a ball bearing cause bigger tides than the moon?

As per the answer to this question it is suggested the relative tidal pull of objects of equal angular area is equal to their relative density. Which lead me to the click-baity question: Does a ball ...
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0answers
20 views

What is a simple model to find the jump height for the Thomson's Jumping Ring experiment?

I'm trying to devise a basic formula that could give a rough estimate for the jump height reached in the Thomson's Jumping Ring experiment, as detailed here. However, it's pretty difficult as most ...
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21 views

Kinetic energy vs Kinetic Energy scenario in a collision, mechanical energy used for work?

Most collisions have Kinetic energy conserved or in the case of inelastic collisions energy is lost into other forms. Though the equation of "TMEi + Wnc =TMEf" is true however, what if two unequal ...
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20 views

How to measure the properties of a non-newtonian fluid?

We have made non-newtonian fluid by mixing water (or Tonic) and starch. We can't figure out the link between the amount of water and starch and the viscosity of the fluid. What we can figure out is ...
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0answers
31 views

Superstring mass between 2 D-branes

The mass of a superstring between 2 parallel D-branes of dimension $p$ and $q$ is $$m^2=(N−a)+(y/2π)^2$$ But what is the value of the normal ordering constant $a$?
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92 views

On the nature of forces in general relativity

*** EDIT: I understand that it's not wise to fixate on Schroedinger words, however their meaning still remains obscure to me. Besides this my question on the possibility to abandon the concept of ...
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0answers
68 views

Free body diagram of pulley

Is there any difference between the free body diagram of fixed pulley and movable pulley? I've read that both of the rope of fixed pulley and movable pulley have the same direction (both upwards or ...
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0answers
150 views

Why do trees sway?

Resonance can also occur in three dimensions (such as wind induced swaying) I tried to make a free body diagram (I know it is terribly wrong) to find the forces that causes the tree to undergo ...
1
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0answers
139 views

Centripetal force at the pole is different from the equator

why is the centripetal acceleration in the poles and equator if different? I know that it's related to Equatorial budge. But what I don't get it is that the centripetal force is zero at the poles. ...
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0answers
14 views

Field line Direction and exerted force

Magnetic field lines of a magnetic field have different directions. What information about the force exerted on a charge will give us the direction of field lines?
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30 views

Relationship between magnetic force acted upon a diamagnetic substance and the magnetic field applied to it

I have a sample of bismuth that I have applied a measured B-field to through the use of a solenoid electromagnet. I've been trying to find a formula relating the B-field to the force that the bismuth ...
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0answers
38 views

Thermodynamic derivation of condition for equilibrium of triple line

Edit:(4/1/2016) Okay, I get how the required equation arises from force balance. All forces are acting on the same length, so the length cancels out of the equation and what we've got is essentially ...
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0answers
36 views

work done in observer frame

I had a few questions. 1) Is work done independent of the refrance frame? 2) Suppose a cart-A with rough surface is accelerating with an acceleration a and another cart-B with acceleration b. Now to ...
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0answers
78 views

Uranus, the Physical model to change it's rotation axle

Uranus rotates pretty wierd, it's 90-degrees tilted; Why is Uranus's axis of rotation tilted? The best answer for this is; that at a distant point in its past, Uranus was struck by a very ...
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0answers
76 views

Potential Energy of two masses

If two particles with masses $m_1$ and $m_2$ interact and are located at $\vec{s_1}$ and $\vec{s_2}$ have their potential energy $U$ defined by the modulus of their position vectors, how would I ...
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0answers
59 views

Friction of an object falling between two walls

I'm simplifying this problem into 2D for easier understanding. Lets say we have 2 vertical walls separated by distance x. Inside these walls I place an object that is only slightly smaller than x in ...
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0answers
37 views

irreversibility Aristoteles law of motion

I am watching the second lecture from the theoretical minimum and do not understand the argumentation of Susskind. For those who do not want to watch the video. It is about the law of motion from ...
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0answers
56 views

Magnetic levitation project

For the past four years, I have been working on a project that will allow permanent magnets to levitate stably above a magnetic surface. So far I have tested my first theory which was to see if ...
1
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0answers
99 views

Impact Force/Pressure of a wave on a vertical wall given PIV velocity field

I have PIV (Particle Image Velocimetry) data of liquid sloshing on a rectangular tank which produces a wave impacting one of the vertical walls. In the picture below you can see the wave about to hit ...
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0answers
67 views

Find the force and the torque so that the cylinder is in balance

At the cylinder of the picture there are static pressures from environment fluid of density $\rho$. If we neglect the atmospheric pressure, calculate how much force and how much torque is needed so ...
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0answers
36 views

Solenoid expressions

I am wanting an expression for the nearly uniform force (not magnetic force) through the central axis of a solenoid, with a nonmagnetic tube but coiled wires with fixed current, and an explanation of ...
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0answers
136 views

Motion in a vertical circle and forces in polar coordinates

Suppose a particle with mass $m$ is whirled at instantaneous speed $v$ on the end of a string of length $R$ in a vertical circle. Let $\theta$ be the angle the string makes with the horizontal. I know ...
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0answers
101 views

Mass flow rate and force on moving disk

If I understood correctly, the force $F$ related to a given mass flow rate $\dot{m}$ through orifice area $A$ (or, say, on a disk of area $A$) is given by Newton's 2nd law of motion - assuming a ...
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0answers
59 views

Is there a typology of different fundamental physical objects?

As I understand it (and of course, I may be wrong!).... In classical mechanics, all objects are basically the same in the sense that They are composed of atoms bunched together. These atoms occupy ...
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0answers
93 views

Discernible “frequencies” of magnetic fields that do not affect each other

Two magnets secured to a surface close to each other in a fashion such that their constant attraction to one another is counteracted by the normal force of the securement of each. Is there a way to ...
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0answers
763 views

Calculating the torque required to move a heavy object (the calculations)

I wanna choose a motor for my bicycle and turn it into an electric one. So the physics part shoots. The force (Force=Mass x acceleration) that i will exert on earth surface(weight) will be my mass*g,...
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149 views

How strong is the force of space expansion?

There are many questions about space expansion, its cause, or its effects. But I have the feeling we never get straight and simple answers. I do not expect answers to be simple in general, but I ...