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[ Official ] How was the Prelims 2021 paper?

How was the paper guys ? 

jack_Sparrow,curious_kidand28 otherslike this
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@Captainnerd yaar lekin fir toh har cheez straight line par travel karegi agr uspar force nahin padegi toh , even a ball thrown from Earth .. I accept iska matlab yeh hoga ki ball has same speed too similar to light toh woh statement bhi galat hoga .. But read this 

Albert Einstein, in his theory of special relativity, determined that the laws of physics are the same for all non-accelerating observers, and he showed that the speed of light within a vacuum is the same no matter the speed at which an observer travels

this is not applicable for other things…

Rest assured , if It has answer other than D, I will quit my preparation for good..
Tag me when the answer key comes 
Agar yeh bhi sahi nahin hua after doing so much courses on light in engineering, I will admit I lack basics and will quit the whole preparation 


mickeyviru,Denisovan2019and1 otherslike this
4.2k views
@Denisovan2019 LOL HE IS SENIOR TO ME BY 4 YEARS FROM SAME SCHOOL .NEVER KNEW DPS HAD SUCH SHIT


plmokn25688524,konkankohinoor
5.2k views

Ab samjh me a raha phd waale bihar group d ka exam kyun dete hain :joy:

plmokn25688524,
4.4k views

EiChansaid

@Captainnerd yaar lekin fir toh har cheez straight line par travel karegi agr uspar force padegi toh , even a ball thrown from Earth .. I accept iska matlab yeh hoga ki ball has same speed too similar to light toh woh statement bhi galat hoga .. But read this 

Albert Einstein, in his theory of special relativity, determined that the laws of physics are the same for all non-accelerating observers, and he showed that the speed of light within a vacuum is the same no matter the speed at which an observer travels

this is not applicable for other things…

Rest assured , if It has answer other than D, I will quit my preparation for good..
Tag me when the answer key comes 
Agar yeh bhi sahi nahin hua after doing so much courses on light , I will admit I lack basics and will quit the whole preparation 


bro you are hundred percent correct. 

5.8k views
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bhai thoda to sharm karo kitni mehnat karwaoge.

""light travels in a straight line in Class VI; it does not do so in Class XII and beyond!""

this line is copied from and given in link of class 12 ncert physicsChapter-10.pmd (ncert.nic.in)   see blue box page 3/35 bhai ever heard of wave optics ya science background se nahi ho ?  

now look at option c "c) Light always travels in straight line. " yahipar  wrong prove ho gaya na?

 ek aur baat jo change nahi ho use CONSTANT kehte he. look at the list of constants in this ncert pdf in appendix 3 . speed of light is at top Appendices and Answers.PMD (ncert.nic.in) 

if you are wrong accept it instead of fighting againt your own self. break open your cocoon of utopia. bhai matlab easy questions ko bina baat ke uljha rahe ho atleast research to kia karo. doosre log distract hote he. 

Bro yahi to context poocha hai ki astronomical distance measurement mein light always straight line mein travel karta hai ye fact ko consider kiya jata hai taki jo normal gravity wo sab ka bending phenomena hai wo sab ko ignore kar sake aur simply fir distance calculate kiya ja sake. Aise sirf agar poochta light travels always in straight line to ye galat statement hoti main is baat se agree karta hun. But astronomical measurement ke liye hum ye assume karte hain ki ye straight line mein travel karte hain taki jo bhi associated issues honge bending wo sab ko ignore karke distance find out kar sake.

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Admin please block this person! He is creating menace here.@Sunnyle
Pam123,wertyuiuygfdfghnand1 otherslike this
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@Denisovan2019 WASTED 1 HOUR WAS STUDYING PEACEFULLY


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Many people are telling to consider the doubtful questions as wrong.. but how many double questions are there? I mark the following doubtful questions-

Copper smelting d

Pressure cooker d

State a

Indus - chenab

Rtc- 2&3

Mitochondria- a

Virus - d

Magnetite- d

EPFO 2&3

Art 32

British model c

Federalism a

Copper smelting D

pressure cooker 1 and 3 only 

article 14 for uncontrolled legislation

Temperature for Sure hoga. ISOCHORIC PROCESS HAI NA KI ISOTHERM OR ADIABATIC.

Confirmed. 

Bhai jab closed system honge especially like the case of pressure cooker to inside ke mechanism steam ke pressure se hi achieve hote hain to outside ke heat flow aur temperature ke scale se sirf delay aur rapid ka fark aayega

Nahi. Aisa impossible hai Energy kaise conserve kroge fir ? bina temp rise ke ? 

Jo aap bol rhe ho woh Isotherm process hai ie temp constant rahe.

Yeh Baat ka proof hai aapke pass koi ? toh please share ? Pressure cooker ki thermo ISOCHORIC hoti hai .. 


Jai Shree Ram !


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@Captainnerd ""expressed in another unit known as light year. It is the distance travelled by light in one year. Remember that the speed of light is about 300,000 km per second. Thus, the distance of the Sun from the Earth may be said to be about 8 light minutes. The distance of Alpha Centauri is about 4.3 light years. given in Chapter-17.pmd (ncert.nic.in) """"and   "" light year is a measure of distance and not of time. Light travels at a speed of 300,000 km/second. Considering this, the distances the light will travel in one year is taken to be one light year. This equals to 9.4611012 km. The mean distance between the sun and the earth is 149,598,000 km. In terms of light years, it is 8.311minute""" in chapter-2 (ncert.nic.in) saying last time option D is correct, aage apki marzi jiii lo apne juth ke sath 


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@babu_bisleri omg, has this not been settled yet??
temperature of the flame does not matter.
If you want proof, check what the usual temperature of a flame is. It is usually upwards of 500 degrees. Temperature at which food is cooked is much lower than that. At 500 degrees, you will be eating charcoal

Also, thermodynamically, P=T, in a closed system. A closed system is one where there is no exchange of mass with surroundings. Till the whistle goes off, a cooker is a closed system. The whistle goes off when the cooker hits the maximum temperature possible, which will be much lower than the flame temperature


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IIT SEH NHI HAI BUT KAFI KHUSH HAI LIFE MEIN WEIRD MAJAK KARKE FAKE PDF SEH DIL NHI BHELATE. IAS NHI BHI BANEGE SAME HI RAHNGEE PHIR BHI
wertyuiuygfdfghn,
4.7k views
@prachimalik1121311 bhai apko kya lagta he isne esa username kyu rakha. master distractor he ye yaha ise ignore karo bass


prachimalik1121311,Udit_pathakand1 otherslike this
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@rawhull NEW SAW SUCH GENRE OF PEOPLE


wertyuiuygfdfghn,
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EiChansaid

@Captainnerd Matlab Yaar kuch bhi to prove your answer 

Newton's first law states that if a body is at rest or moving at a constant speed in a straight line, it will remain at rest or keep moving in a straight line at constant speed unless it is acted upon by a force 

If there is no force acting everything will travel straight !!!! 

Regarding light , it will bend around stars , blackholes etc .. So you can disprove that also

Answer will be D because most of space is vacuum where light has constant speed

We are not using light year to measure Earth’s atmosphere (it is too small for that)
Even for a large dust cloud near a supernova, light year will be measured because in that also much of the space is empty !!!!


.

4.4k views

oopsiesaid

@babu_bisleri omg, has this not been settled yet??
temperature of the flame does not matter.
If you want proof, check what the usual temperature of a flame is. It is usually upwards of 500 degrees. Temperature at which food is cooked is much lower than that. At 500 degrees, you will be eating charcoal

Also, thermodynamically, P=T, in a closed system. A closed system is one where there is no exchange of mass with surroundings. Till the whistle goes off, a cooker is a closed system. The whistle goes off when the cooker hits the maximum temperature possible, which will be much lower than the flame temperature


Lol

Closed system me heat transfer hota hai. Adiabatic system me nhi hota. Who is talking about mass here. Heat is definitely transferred. :)

due to external heat food gets heated and pressure of the system increased and hence the whistle. 

P = T as temp inc P inc and hence the whistle which is for security purpose. Temp things is so naive and common.

It is very basic thermodynamics, not even class XI.

Are you from humanities background ?



Jai Shree Ram !


3.4k views

See this

I am feeling so ashamed of sharing such kid level science. How steam takes heat.

https://www.toppr.com/ask/question/in-a-pressure-cooker-the-cooking-is-fast-because/


Jai Shree Ram !


3.2k views
@babu_bisleri haha, forget my background and let's not resort to personal attacks. Heat is definitely transferred. That's why the food gets heated. Heat can escape from the system too. But that does not affect the maximum possible temperature in a cooker. It is independent of the flame temperature. The flame temperature can be any value higher than the temperature of the cooker. Then there will be a temperature gradient and the flame will heat the cooker. I can't explain any more than this



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As the water reaches the boiling point the heat energy doesnot increase its temperature but is used to change the state of water from liquid to gas by overcoming the force of attraction
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kya decide hua cooker ka?
Udit_pathak,
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