All Questions
10
questions
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42
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Details on why temperature is lower at high altitude
I have read at so many places that warmer air moves up as hotter substances expands and as it rises it loses its kinetic energy and it gets converted into its potential energy(gravitational+...
1
vote
2
answers
1k
views
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
-3
votes
1
answer
124
views
What if 1st law of motion and 2nd law of thermodynamics contradict?
Assume a large flat surface with a pile of books on it somewhere. Assume this system to be isolated and gravity to be present there. Also assume there to be a flow of time.
As now you have ...
- 119
2
votes
2
answers
775
views
How does the work-energy theorem relate to the first law of thermodynamics?
The work energy theorem states that the net work on a particle is equal to the change in the kinetic energy of the particle:
$$W_{net}=\Delta K $$
My first question is whether this formula (the work-...
- 1,581
2
votes
3
answers
1k
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Why do we need an absolute temperature scale?
I am a high school student and I am little confused in thermometry,
My textbook says that, "the liquid in glass thermometer might read the same temp. at the chosen reference points i.e boiling ...
- 470
0
votes
1
answer
104
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First principle of thermodynamics vs classical mechanics
please I need clarification about the first principle of thermodynamics, it's general statement is:
$$\Delta U + \Delta \text{KE} + \Delta \text{PE}= W + Q .$$
Supposing that: $ΔU = 0$ and $Q = 0$, ...
1
vote
1
answer
25
views
Are the magnitudes of the forces in activity in the two sides of a piston always the same?
This question has come to my mind when I was learning about pressure-volume work.
I was told that the pressures applied on both sides of a massless piston is always the same. So, since
F = P/A,
I have ...
2
votes
1
answer
84
views
Why don't comets just vapourize away?
As far as I know, comets are in a freefall around the sun. That would mean, net acceleration due to gravity is almost zero because R =m (g-a) where R is reaction force. Now pressure is force per ...
- 61
1
vote
3
answers
787
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Comparing work in thermodynamics with work done in mechanics
Let us the consider a gas as our system enclosed in a cylinder with piston.
1st case(Expansion of gas):
Here force on the piston is exerted by the gas in upward direction and during expansion piston ...
- 79
6
votes
1
answer
197
views
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 ...
- 161