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4
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3answers
54 views

Why do Temperatures Equalize

I have some Oxygen at Temp A in one container and some Nitrogen at Temp B in another container. If I mix these two containers eventually both the Oxygen and Nitrogen will be at the same temperature. ...
1
vote
0answers
77 views

Ball Rotating in Place Under Waterfall

https://www.youtube.com/watch?v=Khf6koh3IO8 Can anyone help me explain this? It seems like the ball should shoot out from underneath. I have two main theories. 1) Bernoulli's Principle says that the ...
0
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0answers
13 views

Easiest way to levitate a ferromagnetic material that is not a permanent magnet?

I want to levitate an iron cube that is not a polarized permanent magnet. What is the easiest way to do this?
0
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0answers
13 views

Can a diamagnetic levitator levitate non-permanent ferromagnetic materials?

I am building a diamagnetic levitator that will eventually levitate a small neodymium cube. However, is it also possible for an iron cube to be levitated as well? I know that diamagnetic materials ...
0
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1answer
30 views

Is it possible to levitate large objects through diamagnetic levitation?

I am currently building a diamagnetic levitator with a strong neodymium magnet, two slabs of bismuth (a diamagnetic material), and a small neodymium cube to levitate. However, I was wondering if it ...
0
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3answers
46 views

The principle behind Inertia and it's connection to Equilibrium

Inertia is the tendency of a force-free body to remain in that state or it is something that opposes any act of changing its equilibrium state. Mass is a measure of inertia. I have some questions ...
0
votes
1answer
38 views

How does distance affect force?

In the image below, the system is in equilibrium. Some force is applied at the bottom of the vertical pole and is being opposed by some force at the top by the horizontal pole... But I feel as though ...
1
vote
1answer
33 views

Equilibrium of a Solid Body

To find the torques around B, see the figure below, I took the cross product as followed: and we know that $W=160 N$ but when I insert that value into the the equation in the red box, I get ...
0
votes
1answer
21 views

I need help with determining angles after shifting of axis in Free Body Diagrams

I can't figure out by which property of the triangle the angles in shifted axis are also 30 degrees. Vertical angle theorom doesn't work. I drew it again and again. If someone could draw me a ...
1
vote
1answer
52 views

Massless ladder against a frictionless wall [closed]

I am confused by a review problem for my physics course. I keep getting a different answer from the solution (which was given to us) and not sure what I am missing. A massless ladder has a length of ...
11
votes
7answers
1k views

Why doesn't an object, despite having a non-zero potential energy stored in it, fall by itself from the elevation?

When an object is at a certain height, it has some energy stored in it as we have done some work on it to get it to that height. So when it already has energy, then why doesn't it fall off from the ...
0
votes
2answers
29 views

Calculating the time for two bodies to reach thermodynamic equilibrium

If we have two bodies a and b, with temperatures $T_a$ and $T_b$ respectively, with $T_a > T_b$ and we also know that body b is surrounded by body a completely. How do we calculate the relaxation ...
0
votes
2answers
71 views

Angular equilibrium on a see-saw

I have a tonne of questions related to see-saw equilibrium because most places I've been to online only deal with horizontal equilibrium - but static equilibrium can occur on an angle too. My ...
0
votes
0answers
17 views

How is equilibrium achieved when masses are unbalanced?

Consider the see-saw scenario shown below (This image was from a Phet simulation) If you place a 5kg mass 0.25m from the pivot point, the seesaw will have net torque in an anticlockwise direction, ...
0
votes
1answer
30 views

Basic tension and equilibrium confusion

The following is what I did: $$Fsin\theta = 60 => F = 93 N$$ $$Fcos\theta = 40 => F = 52 N$$ Why do I get different results? Does this mean the object isn't in equilibrium? How can I ...
0
votes
1answer
35 views

Gas/liquid pressure equilibrium of water in an exotic environments

So I'll preface this by saying this is not some evil homework assignment, this came about from some idle talk of colonizing the moon by a couple of software engineers when we realized we had no idea ...
3
votes
1answer
45 views

Conservation of Energy of two charged blocks connected by light spring

Two identical blocks resting on a frictionless, horizontal surface are connected by a light spring having a spring constant $k = 100 N/m$ and an unstretched length $L_i=0.400 m$. A charge $Q$ ...
0
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0answers
14 views

A body acting by zero net external force

I wonder, for a rigid body, if the vector sum of all external forces acting on it equals zero (Fnet = 0), does it also leads to the vector sum of all external torques acting on it about any point ...
3
votes
1answer
41 views

Difference between state variable and state function in thermodynamic?

I think these two terms are sometimes used as synonyms and other times as different concepts. Can some explain what is the difference? An example would be good. Also, can state variable be the state ...
2
votes
3answers
108 views

Rate at which a pendulum bob slows due to air resistance?

I know that "perfect" pendulums would be able to swing forever, unperturbed by air resistance. However, since there is air resistance around us, pendulums (swinging bobs) slow down and move closer and ...
1
vote
0answers
102 views

Three-log problem [closed]

Three uniform round rigid cylindrical logs of the same size and weight are placed on a horizontal plane. The two at the bottom are touching each other, the third one is placed on the top as shown in ...
1
vote
0answers
30 views

Are these torques correct for a simple balancing/fulcrum experiment?

For my physics lab, they had us do a simple static equilibrium experiment where we rested a ruler on a fulcrum (at its center of mass) and then attached varying amounts of weight on either end at ...
0
votes
2answers
48 views

Angles in a static equilibrium

I have three masses (Fα, Fβ & Fg) with 2 pulleys, and a wind variable which is in static equilibrium. I have already calculated the appropriate forces for the 3 masses by multiplying it with ...
0
votes
1answer
29 views

A counterexample to the Law of Stable Equilibrium?

This is the "Law of Stable Equilibrium", according to Hatsopoulos and Keenan: A system having specified allowed states and an upper bound in volume can reach from any given state one and only ...
0
votes
0answers
36 views

Mechanical equivalent of heat => transfer from work W to heat Q

Consider the following experiment to determine the mechanical equivalent of heat $\mu = \frac{\Delta W}{\Delta Q}$ Not seen in the picture is a weight with known mass hanging down the cord. When you ...
-1
votes
1answer
50 views

Find the indicated quantities from the given data [closed]

This is a vector application. A rope is hung at both ends from a horizontal beam, and a weight m is suspended from it as shown in the figure. The left part of the rope exerts a force G at P, while ...
3
votes
0answers
29 views

Timescales of physical and chemical equilibrium

Background When describing the behaviour of a reacting systems, we usually don't hesitate to apply property models to relate the local properties of each species. For example, in the case of a gas ...
3
votes
1answer
48 views

Do all equillibrium points of a discrete mapping show up on the bifurcation diagram?

The question in the title is perhaps vaguely posed, so I'll include the concrete example which is bugging me. Suppose we have a mapping given by $$N_{t+1}=N_t\cdot ...
0
votes
2answers
25 views

What determines whether a mobile will hang in stable or unstable equilibrium?

Asking for a friend trying to make a Calder-style hanging mobile: https://www.google.com/search?q=mobile+calder&tbm=isch I understand torque just well enough to get it to balance (theoretically). ...
23
votes
2answers
2k views

Why do most office chairs have 5 wheels?

(Inspired by Why are four legged chairs so common?) I've been wondering for a while... Why do most wheeled office chairs have 5 wheels? My guess would be that while stability vs. simplicity ...
0
votes
1answer
52 views

Functions of state and definition of equilibrium

Consider this - A function of state is any physical quantity that has a well-defined value for each equilibrium state of the system. (Blundell and Blundell - Thermal Physics) My question is - Are ...
-1
votes
1answer
44 views

Two strings in static equilibrium. Why not use the pythagorean theorem to combine vectors? [closed]

I have been working through a physics course and came across the problem: two strings holding a weight in static equilibrium. It all made sense, except for this: Why don't you use pythagorean theorem ...
0
votes
2answers
81 views

Why don't barbells tip over when a 45 is placed on one side?

A standard barbell is 45 pounds, as is the heaviest weight available in most gyms. When a weight is placed on the side of a barbell, some of the barbell is to the "outside" of the weight, like so, so ...
1
vote
1answer
55 views

If two gasses are in thermal equilbrium, do their molecules have same amount of Kinetic energy?

If two gasses are in thermal equilbrium, do their molecules have same amount of Kinetic energy?
0
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0answers
36 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 ...
1
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0answers
44 views

Why dynamic equilibrium exists?

We know that at equilibrium Gibbs energy is minimum. We also know that at equilibrium both forward and reverse reactions occur simultaneously, and also we know that for a reaction to be spontaneous ...
0
votes
0answers
27 views

In stochastic thermodynamics, can you define the notion of equilibrium for microstates/individual trajectories?

Recently there has been quite some research on interpreting statistical thermodynamical quantities at the level of microstates/individual trajectories. Although I did not find any ...
0
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1answer
48 views

Orbital but stationary motion

Is there a place between the Moon and Earth where an object can rest freely and revolve with the Moon? What is that called?
0
votes
2answers
50 views

Equilibrium on a fixed wedge

While solving a question I came acrross this doubt.For a block in equilibrium on an inclined wedge, the summation of forces should be equal to zero.I am confused because I got two different results ...
0
votes
1answer
43 views

Why there is an extra componet of force in this Equilibrium state?

I have a question about the forces on a body at equilibrium. Look to this image: here i draw a man standing with a pen on earth. And I think that I draw all possible forces on it. They are as ...
1
vote
0answers
56 views

In an equilibrium of two systems, why is not true that $\frac{\delta S_{1}}{\delta N_{1}} = \frac{\delta S_{2}}{\delta N_{2}}$?

Why is not true that $\frac{\delta S_{1}}{\delta N_{1}} = \frac{\delta S_{2}}{\delta N_{2}}$ across two systems that exchange particles? It is true, instead, that $\frac{\delta F_{1}}{\delta N_{1}} = ...
0
votes
0answers
22 views

Finding pressure as a function of height from centre

How do you find the pressure as a function of height from the centre(geometric) of any rigid body (hollow) of negligible mass when it contains a fluid of density D filled completely and is static, ...
1
vote
1answer
92 views

Discrete time simulation of gas liquid equilibrium in a tank

I am trying to write a discrete time simulation of liquid/gaseous oxygen in a pressurised cryogenic fuel tank. For now I am assuming that the only external change to the system is the influx of heat ...
0
votes
0answers
42 views

Point of zero gravity for fixed masses?

Given a number of fixed point masses in 3D space, is there necessarily one or more points where there is zero gravity (ie, the combined gravity of the masses cancels out), and, if so, how do I find ...
2
votes
1answer
84 views

Volume as a choice of measure in phase space

For equilibrium systems, we expect the Liouville theorem to hold. This theorem states that the density function of the states of the system is a constant of motion, which in turn can be translated ...
0
votes
1answer
49 views

Conceptual Ice Water Equilibrium

We observe that when we apply pressure on on Ice Water equilibrium system then more of ice melts.. Ice(more Volume) + Heat ----><----- Water (Less volume) If we increase pressure then volume ...
0
votes
2answers
63 views

Why does the mass on the cart-pole have to fall?

Not sure if I am posting this question in the correct community, as it relates primarily to reinforcement learning. Apologies early on if this is not so. In reinforcement learning many algorithms ...
0
votes
1answer
28 views

Can there be net condensation into a pool of water?

I'm curious about the equilibrium of evaporation and condensation. Given that the surface area of a dehumidifier's evaporation coil at 4C is proportional to the rate of condensation, how would the ...
1
vote
1answer
43 views
1
vote
0answers
38 views

Roberval Balance [closed]

Is there any mathematical/mechanical article that explains in detail why the Roberval balance is taken place? I generally observed that the classical mechanisms are not analysed in detail, even in ...