[ Official ] How was the Prelims 2021 paper?
How was the paper guys ?
@Guesswhoshere whistle weight is part of lid ,isn't it .it comes attached
both types of pressure cookers are there. But i guess the common standard ones do have removable whistle weights.
Jesse_pinkman,
Just a doubt regarding the pressure cooker q, why are all keys saying that temperature of the flame doesn’t matter. So does it, doesn’t?
It doesn't. It's basic thermodynamics. If you have a science background, read the rest
A pressure cooker is an example of a closed system
For closed systems, ideal gas equation is PV = nRT (Pressure*Volume = a constant(nR)*Temperature)
Volume, nR are constant
Hence Pressure and Temperature are directly proportional
A pressure cooker is designed to operate at a maximum pressure - which depends on the strength of the material etc.
The temperature at which cooking happens will depend on that pressure only
Pam123,sleeplessnights89
shaanu4595684,With respect to the Pressure cooker question:
At constant volume increasing pressure increases temperature. However, to increase the pressure there has to be some source so as to fulfill the law of conservation of energy. Pressure cannot increase on its own.
heat and temperature are two different things.
It's similar to wind and pressure gradient in geography. Wind will blow from higher pressure to lower pressure
Similarly heat will flow from higher temperature to lower temperature
As long as the temperature of the flame is any value higher than the temperature of the cooker, the flame can heat the cooker
sleeplessnights89,
Guys when the entire Meaning of the 3rd statement is changed, even 1&3 seems to be wrong. 1 only should be the answer which isn’t given. According to me, there are high chances for pressure cooker question to be deleted.
Questions dnt get deleted like this. Upsc will never accept it's mistake. They will just come up with an ans which can be anything between 1 and 2,1 and 3,1 2 and 3. They anyways release ans key after final result and by that time none of the arguments we are making will matter. Every year some questions are controversial(for aspirants and not for upsc) but such questions never get deleted. Only Outright blunders like translating civil disobedience movement as non coop mvmt, as was done in 2020 ,have chance of getting deleted. If there's even 1% scope of question being correct,upsc will not delete it.
One can go to the court(like 2017) but thn upsc has its own way of handling things and it will win(like 2017).
Master,
Just a doubt regarding the pressure cooker q, why are all keys saying that temperature of the flame doesn’t matter. So does it, doesn’t?It doesn't. It's basic thermodynamics. If you have a science background, read the rest
A pressure cooker is an example of a closed system
For closed systems, ideal gas equation is PV = nRT (Pressure*Volume = a constant(nR)*Temperature)
Volume, nR are constant
Hence Pressure and Temperature are directly proportional
A pressure cooker is designed to operate at a maximum pressure - which depends on the strength of the material etc.
The temperature at which cooking happens will depend on that pressure only
But it is not adiabatic either so outside heat will affect the inside of the system
Temp from outside definitely have an effect.
Jai Shree Ram !
yeah that’s true. But I hope, they cancel the question due to two reasons :1. the word “ maximum” is missing in the question. The maximum temperature doesn’t depend on temp of the flame ( it’s given in UPPCS 1995 prelims which is being quoted by few people ).2. Upsc didn’t even copy the question fromthat guide correctly. It’s given as weight on the lid in both uppcs as well as that question bank.So there is a mistake in the question as well as the options. So let’s hope it gets deleted. The worst possible thing is, they ignore the concept as well as generalist approach and just give the answer as 1&2. But that’s meaningless. So let’s see.All the best
UPPCS question does not mark that temperature is wrong.
In that only 2 things was mentioned and no combination fits for temperature one from the options. Does not mean temperature was Wrong.
Jai Shree Ram !
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