# Tagged Questions

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### 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 ...
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### 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?
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### 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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### 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 ...
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### 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 interpretation/...
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### 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?
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### 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 ...
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### 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 ...
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### Local and global detailed balance

I'm taking a course on nonequilibrium statistical mechanics and I encountered the terms local and global detailed balance. I'm a bit confused about what is their exact definition and what is the ...
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### Is it possible to have a line rather than a point where the three states of a substance can exist?

Most of us are familiar with state diagrams that define which of the three states a substance will take given the pressure and temperature. And that some substances, such as water for example, exhibit ...
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### Why should slope of pressure versus volume always be negative?

I read that the slope of the pressure, ($P$), versus volume ($V$) graph should always be negative for thermodynamic stability, but there was no further explanation in the text. Could someone give an ...
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### Mechanical equilibrium : thermodynamics and classical mechanics

A similar question was asked here but mine is a bit different. In thermodynamics, a mechanical equilibrium is defined as a uniform pressure (for a fluid). In classical mechanics, equilibrium is ...
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### Where do forces point in an equilibrium system

I have the system above, with three identical balls of weight $W$ and radius $r$. The angle joining the centres is $\theta$, and the coefficient of friction between the balls and the plane is $\mu$ ...
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### How to calculate the normal force exerted by a fulcrum off-center?

So I know that $F_N$ exerted by a fulcrum right under the centre of mass for, say, a long horizontal rod, is equal to $mg$. But what if the fulcrum is off the centre of mass either to the right or the ...
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### How many bricks can be put without disordering the equilibrium? [closed]

A homogenous brick with length L, is on a horizontal surface. On this brick are put one after another other bricks, which are the same with the first. Every brick is moved along L/5 units horizontally ...
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### Checking for equilibrium in a square configuration of charges [closed]

Four equal positive charges each of magnitude q are placed at the respective vertices of a square of side length l. A point Q is placed at the centre of the square. Then find the state of equilibrium ...
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### $N>2$ gravitating masses can never reach equilibrium [closed]

If you have $N>2$ point masses, each attracted to each other by the force of gravity, how could you go about showing that they will never reach equilibrium?
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### Equilibrium when it shouldn't be?

I'm doing an experiment that requires me to balance a ring, tied to four strings, in the middle of a force table; in other words, the objective is to set the ring at equilibrium. Each string is ...
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### Rotational Equilibrium Problem [closed]

The question is as follows: One end of a uniform 4.0-m rod, whose weight is w, is supported by a cable that makes an angle of 37° with the horizontal. The other end of the bar rests against a wall ...
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### Temperature in a vacuum made in the lab

Is the thermal energy of a vacuum 0? And, how close to a perfect vacuum can we make in the lab?
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### Deriving the Force on an ion in the Classical Harmonic Crystal

I was following Solid State Physics by Ashcroft and Memrmin and their introduction to the Classical Theory of the Harmonic Crystal. (Chapter 22) If there are a large number of ions in a straight line,...
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### Will heating water vapor induce equilibrium?

What happens to the vapor content if a mixture of gases saturated with water vapor is heated isobarically? Will the amount of liquid water present decrease, yielding up more vapor so as to re-...
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### Find the center of gravity of a system with three spheres [closed]

Three spheres are put on a table. The first sphere, whose mass is 1 kg is 20 cm away from the second whose mass is 2 kg and the third sphere is 100 cm away from the first sphere and has a mass of 5 kg:...
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### What is the theoretical instantaneous temperature of a gas?

When we measure the temperature of a gas we typically integrate the molecular collisions and wind up with an 'average' temperature due to the sensor comprising a relatively large thermal mass. And ...
### Chemical reaction A+B$\leftrightarrow$C. Equilibrium VS Non Equilibrium
Could you please confirm or say why I am wrong? Let us consider the steady state of the chemical reaction $A+B \leftrightarrow^{k_+}_{k_-} C$, with $k_+$ and $k_-$ the forward and backward rates. ...