All Questions
23 questions
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Doubt with Heat and Potential Energy. (Warning: Many Assumptions) [closed]
I had a question in my Textbook which reads as follows,
Before that, we have to assume that the flowing water is ideal.
So, here we have to equate Change in Potential Energy to Heat Energy/Internal ...
1
vote
2
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55
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Stretching vs bending of thin membrane
Stretching refers to the deformation of a material when a tensile (pulling) force is applied. The material elongates along the direction of the applied force.
Bending involves the deformation of a ...
- 241
2
votes
0
answers
59
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How to modify kinetic gas theory to work for macroscopic particles? (2D)
For the first time I framed a question on my own when I was recently playing carrom pool with my cousin and a striking thought ran across my mind!
I was thinking if a square frame is fixed rigidly on ...
1
vote
3
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575
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Work done by free expansion of gas and the energy of the piston
So this has been bothering me for a while. I know that for a free expansion of a gas, work done by it is zero. However, I have a doubt regarding the kinetic energy gained by a piston during this free ...
1
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0
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274
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I want to know: what is the principle that causes this phenomenon? [closed]
The effect of fractal fingering can be observed if a droplet of an ink-alcohol mixture is deposited onto diluted acrylic paint. How are the geometry and dynamics of the fingers influenced by relevant ...
- 11
0
votes
1
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29
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Could a heated coil with a sail to catch the hot air,(in theory) produce enough or any thrust to lift a drone? in the way a hot air balloon works
This is an approach I am thinking of for an alternative to ion propulsion for making silent drones.
- 1
0
votes
0
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621
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Why is the work a function of the mass's pressure?
A gas is confined in a closed container with a movable piston. The container is kept in a hot water bath. Blocks of different known masses are placed on top of the piston one at a time, and the gas is ...
- 9
1
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0
answers
54
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Why does the second piston accelerates slower than first? Why it happens so? [duplicate]
In the image above we can have $A2>A1$.
We know it from Newton second law that $F=m×a$. It means that if we apply large force on any object then, it will accelerate with large value too.
My ...
- 91
1
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2
answers
1k
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Work done by the gas in free expansion
I am a high school student and I am a little confused in a free expansion of gas, My teacher told me that when an ideal gas expands adiabetically against vacuum there is nothing on which the gas does ...
- 470
0
votes
2
answers
105
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How did the derivative shift? (Turbojet Thrust Equation)
While deriving the Turbojet Thrust Equation this is what the author does
$$F=m\cdot a$$
$$F=m\frac{\mathrm{d}v}{\mathrm{d}t}$$
$$F=\frac{\mathrm{d}m}{\mathrm{d}t}v$$
$$F= m^*\cdot v$$
(where $m^*$ is ...
-1
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3
answers
195
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Confusion about whether or not force can be exerted on air
If someone is running in air, the air exerts a force on them i.e. air resistance. However, does the person exert a force on the molecules in the air during their motion. It seems very likely to me but ...
- 105
0
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0
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124
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Why does the wind close doors?
Assume you have two rooms, both with holes in the wall (more commonly known as open windows), which connect each room to the exterior. The two rooms are connected, but the connection can be closed by ...
- 958
2
votes
1
answer
289
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Confusion on flux definition
In the context of fluid mechanics, flux is the quantity per time per area and one could calculate the total movement of that quantity per unit of time through a control surface by
$$\iint{}flux(S,t)...
- 191
0
votes
4
answers
360
views
Would steam engines be possible at zero atmospheric pressure
given that water becomes water vapour at around 0˚C in 0 atmospheric pressure would it be possible to make a steam engine that could exploit this in space?
I understand that the water vapour would ...
- 131
-2
votes
1
answer
91
views
Jet engine and thrust
Let's consider two identical jet engines operating at the same point. The first is attached on a plane's wing which is moving and the second is attached on the ground and remains still in order to be ...
- 75
1
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2
answers
845
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Energy Conversion in Compressor
Let's consider the case of a compressor operating at a certain point. Hypothetically, if this compresson is not attached anywhere it will start moving backwards, as a result of the force due to the ...
- 75
2
votes
1
answer
434
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Joule heating for a fluid
Say you have a conductive liquid with a changing magnetic field going right through it, causing an electric current. How exactly does the electric current travel and how could you calculate the ...
- 21
-2
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1
answer
104
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How to explain the behaviour of tyre smoke [closed]
Please forgive me for being a non-phycisist and new member. I am working on a Visual Effects module for my degree and I need to analyse the behaviour of tyre smoke from a burnout. I know that this ...
0
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2
answers
563
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Effect of wall friction on stagnation pressure and temperature
We have incompressible air flowing through a cylindrical pipe, from section A to section B. The process is considered to be stationary.
My theory book says that, because of the frictional losses on ...
4
votes
2
answers
727
views
How is temperature and pressure related to when a tire rolls on the ground?
Actual observation: Here in Canada it is known that even when 'dry' snow is on the ground, and when a car drives over it that small amount of dry snow instantly becomes ice (NOT GOOD). Anyways as an ...
- 546
1
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0
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75
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hydrodynamic entrance length [developing flow]. Non-native speaker needs some help [closed]
I am currently writing my thesis in English as an non-native speaker. From time to time, I struggle quite a bit with the correct expression of the sentences. Could you have a look on the highlighted ...
- 11
3
votes
3
answers
2k
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Gas pressure and centrifugal force
I think about a rotating torus (simplified tire) filled with ideal gas. Mass of gas is $m$ and molar mass is $M$. Pressure in non rotating torus is $p_0$. Temperature is constant $T$. Inner radius of ...
- 3,074
6
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1
answer
197
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Do vortex tubes work with a reversed end plug?
Would a vortex tube still work if instead of a cone plugged into the 'hot' end you had a smaller hole on the 'cold' end? As I understand it, the point of the cone on the hot end is to only allow the ...
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