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Doubts ! Help Needed

Please give a solution to the below questions.

  1. Please help

    Please help

  2. Please help

    Please help

Note by Rajdeep Dhingra
1 year, 4 months ago

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Congratulations for being selected to represent India in ijso. Also what about JOMPC? Shivam Jadhav · 1 year, 4 months ago

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@Shivam Jadhav rajdeep bhaiya online hai aur onhone ntse ke liye apply kiya tha Real Champ · 2 months, 3 weeks ago

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@Shivam Jadhav Thanks. It will be out day after tomorrow. I have marked all the solutions I'll compile and post it on monday. Rajdeep Dhingra · 1 year, 4 months ago

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@Rajdeep Dhingra ????? Ritik Gandhi · 5 months, 1 week ago

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@Ritik Gandhi JOMC was a contest , I had to take out the result. Rajdeep Dhingra · 5 months, 1 week ago

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@Rajdeep Dhingra bhaiya aapne brilliant premium lifetime ke liye kitna pay kiya tha Real Champ · 2 months, 2 weeks ago

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nishant,ayushman,gaurang inme se kisine ntse clear kiya or aap school ke exams ke samay sirf school ka padte hai ya coaching ka bhi padte hai. Real Champ · 2 months, 3 weeks ago

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bhaiya mai ijso or ipho ke liye prepare kar raha ho toh mai kaise school ke saath use bhi padho or aapke 10 me kitne number thay Real Champ · 2 months, 3 weeks ago

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bhaiya yeh bata dijye ki school me jo course hai(icse) ka since i am in class 10 then how i can maintain a fine balance between academics and competitive study . Real Champ · 2 months, 3 weeks ago

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you are an ijso gold medalist or app to school ke bad coaching allen bhi jaate hai toh fir aap apna time kaise balance karte hai Real Champ · 2 months, 3 weeks ago

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BHAIYA IJSO KE LIYE KAUN SI BOOK SE PADHE AUR ASTRONOMY KE LIYE KISE PADHE Real Champ · 2 months, 3 weeks ago

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bhaiya pls reply Real Champ · 2 months, 3 weeks ago

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bhaiya physics olympiad ke liye kis book se theory padhe aur aapne ne ntse ke liye apply kiya tha Real Champ · 2 months, 3 weeks ago

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rajdeep u r of which coaching allen or fiitjee Real Champ · 3 months, 1 week ago

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@Real Champ I was first in fiitjee , now in allen. Rajdeep Dhingra · 3 months ago

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@Rajdeep Dhingra you are an ijso gold medalist or app to school ke bad coaching allen bhi jaate hai toh fir aap apna time kaise balance karte hai or aap ne allen kis class mai join kiya tha Real Champ · 2 months, 3 weeks ago

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@Rajdeep Dhingra pls help me bhaiya mai koi bhi nse ke paper ke liye kaise apply karo jab mera school register na ho toh since u r an ijso gold medalist u must have an idea about this question aur kya mai class 10 mai nsejs me apply kar sakta ho aapne kis class mai apply nsejs ke liye apply kiya tha.if u have any books then suggest me books for ijso and ipho Real Champ · 2 months, 3 weeks ago

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@Real Champ I applied for NSEJS in class 9th. If your school isn't Registered , go to the nearest KV School and asked them to register you. For NSEJS simply do NCERT 9,10,11.(P,C,B). For maths practice past year papers or extra questions from NTSE type books. Rajdeep Dhingra · 2 months, 3 weeks ago

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@Rajdeep Dhingra bhaiya mai ijso or ipho ke liye prepare kar raha ho toh mai kaise school ke saath use bhi padho or aapke 10 me kitne number thay Real Champ · 2 months, 3 weeks ago

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@Rajdeep Dhingra nishant,ayushman,gaurang inme se kisine ntse clear kiya or aap school ke exams ke samay sirf school ka padte hai ya coaching ka bhi padte hai. Real Champ · 2 months, 3 weeks ago

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@Rajdeep Dhingra i would like to share a simple problem with which u might have suffer.problem is that while preparing for ipho and ijso i am unable to study for boards and whenever i take leave from my school then i used to have scolds from principal of school .what is the average time an student should devote for preparing ipho and for application process in any foreign university like pennsylvania,california,mit.how u made a balance between ur school studies and competitive studies.u appeared for ntse or not. Real Champ · 2 months, 3 weeks ago

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@Rajdeep Dhingra pls reply Real Champ · 2 months, 3 weeks ago

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@Rajdeep Dhingra bhaiya aapne brilliant.org pe register ke liye kitne rupaye pay kiye Real Champ · 2 months, 3 weeks ago

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@Rajdeep Dhingra bhaiya can u suggest me books for ijso Real Champ · 2 months, 3 weeks ago

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@Real Champ i would like to share a simple problem with which u might have suffer.problem is that while preparing for ipho and ijso i am unable to study for boards and whenever i take leave from my school then i used to have scolds from principal of school .what is the average time an student should devote for preparing ipho and for application process in any foreign university like pennsylvania,california,mit.how u made a balance between ur school studies and competitive studies.u appeared for ntse or not. Real Champ · 2 months, 3 weeks ago

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@Real Champ I did appear for NTSE , but couldn't make it to the next round as my SST is poor. Rajdeep Dhingra · 2 months, 3 weeks ago

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@Rajdeep Dhingra similar will be the case with mine since my sst is poor and how to manage time or make a balance between academics and studies for ipho and ijso Real Champ · 2 months, 3 weeks ago

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@Rajdeep Dhingra BHAIYA AAP KI ENGLISH TO KAAFI ACHI AUR ACCURATE HAI AAP TOEFL KE LIYE PRACTICE KAR RAHE HAI KYA Real Champ · 2 months, 3 weeks ago

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@Rajdeep Dhingra BHAIYA CORSERA.ORG IS A VERY GOOD WEBSITE BUT HOW TO LEARN FROM IT Real Champ · 2 months, 3 weeks ago

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@Rajdeep Dhingra BHAIYA AAPNE IJSO AUR IPHO ALONG WITH BOARDS KE LIYE KAISE TIME MANAGEMENT KIYA Real Champ · 2 months, 3 weeks ago

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@Real Champ can u share ur phone number with me as or any mailid on google or yahoo as i ahve a lot of queries regarding nse's exams and how u study from coursera.org Real Champ · 2 months, 3 weeks ago

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Which book is it? Ritik Gandhi · 7 months, 2 weeks ago

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@Ritik Gandhi I answered it before also , an old JEE subjective book. Just Mechanics for JEE is written on the book , nothing else. Rajdeep Dhingra · 7 months, 2 weeks ago

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@Rajdeep Dhingra hi rajdeep bhaiya which all books do u refer for physics olympiad? Rasty Rocky Yoyo · 4 months, 2 weeks ago

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@Rasty Rocky Yoyo Irodov , Past Papers , Arvind Tiwari's Book for practice and Cengage for theory. Rajdeep Dhingra · 4 months, 1 week ago

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@Rajdeep Dhingra how is krotov? Rasty Rocky Yoyo · 4 months, 1 week ago

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@Rasty Rocky Yoyo It is good , like irodov only , but I haven't done it much. Rajdeep Dhingra · 4 months, 1 week ago

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@Rajdeep Dhingra And what about the above book(the one from which you sent questions? Any clue through which I might be able to access the book? Rasty Rocky Yoyo · 4 months, 1 week ago

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@Rasty Rocky Yoyo I think new Editions of it has been published by balaji publications. JEE Mechanics or something like that. Rajdeep Dhingra · 4 months, 1 week ago

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@Rasty Rocky Yoyo Can you please reply? Rasty Rocky Yoyo · 4 months, 1 week ago

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@Rajdeep Dhingra who's the author of the book? Ritik Gandhi · 5 months, 1 week ago

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@Ritik Gandhi I don't know. Rajdeep Dhingra · 5 months, 1 week ago

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@Rajdeep Dhingra publication? Ritik Gandhi · 5 months, 1 week ago

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@Ritik Gandhi Balaji Rajdeep Dhingra · 5 months, 1 week ago

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@Rajdeep Dhingra Ok thank you! Can you please send a pic of the cover page? Ritik Gandhi · 5 months, 1 week ago

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@Ritik Gandhi I don't have the cover page , It is torn. Even the 1st Chapter is missing. Rajdeep Dhingra · 5 months, 1 week ago

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@Rajdeep Dhingra who's the author of the book? Ritik Gandhi · 7 months, 2 weeks ago

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@Ritik Gandhi ?? Ritik Gandhi · 7 months ago

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Bro is your second doubt cleared ? i am getting it's answer as root 5g/7(R-r) tell if not cleared i will give the solution ( if my answer is correct.) . Brilliant Member · 1 year, 1 month ago

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@Brilliant Member Cleared. Thanks anyways. P.S : your answer is correct. Rajdeep Dhingra · 1 year, 1 month ago

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Hey @Rajdeep Dhingra why not coming to fiitjee ? PLease tell the truth !! Parth Bhardwaj · 1 year, 1 month ago

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@Parth Bhardwaj rajdeep u are of which coaching allen or fiitjee Real Champ · 3 months, 1 week ago

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Which book is it ? John Verghese · 1 year, 3 months ago

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@John Verghese I don't know. Some old book for JEE subjective. Rajdeep Dhingra · 1 year, 3 months ago

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Hy rajdeep, can u give some tips for prepartion of nsejs , as my brother will be giving this year, presently he is in class 9. Rahul Bubna · 1 year, 3 months ago

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@Rahul Bubna Read 9th and 10th class NCERT books thoroughly , if possible read 11th and 12th class NCERT also.(only relevant topics). For NSEJS most important is your speed of solving questions. Rajdeep Dhingra · 1 year, 3 months ago

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@Rajdeep Dhingra If he starts from June 10 , is he will be able to clear nsejs ? He also goes to coaching ... Rahul Bubna · 1 year, 3 months ago

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@Rahul Bubna I think so. Rajdeep Dhingra · 1 year, 3 months ago

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Question 2:
Let \( f \)denote the friction force acting on the body. Now, ablut the center of mass writing the torque equation,
\( f \cdot r = \dfrac{MR^{2}\alpha}{2} \)
\( f = \dfrac{MR\alpha}{2} \)
But since the cylinder doesn't slip \( r \alpha = a_{cm} \)
\( f = \dfrac{ma_{cm}}{2} \) Now,
\( mg\sin(\theta) - f = ma_{cm} \)
\( mg\sin(\theta) = \dfrac{3ma_{cm}}{2} \)
\( a_{cm} = \dfrac{2g\sin(\theta)}{3} \)
\( \alpha = \dfrac{2g \sin(\theta)}{3r} \)
For small values of \( \theta \), \( \sin(\theta) \approx \theta \)
\( \alpha = - \dfrac{2g \theta}{3r} \)
The negative sign just denotes that direction of alpha is opposite to displacement.
This is the rotational analogue of \( a = -\omega^{2}x \)
\( \therefore \omega = \sqrt{\dfrac{2g}{3r}} \)
Frequency \( \dfrac{\omega}{2\pi} = \dfrac{1}{2\pi} \sqrt{\dfrac{2g}{3r}} \) Vighnesh Shenoy · 1 year, 4 months ago

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@Vighnesh Shenoy It is wrong bro. \( \theta\) is the angle you moved the center of mass not the angle by which you rotated the sphere. Hence you can't equate \( {\omega}^2 \) to \(\dfrac{2g}{3r}\). Rajdeep Dhingra · 1 year, 2 months ago

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@Rajdeep Dhingra it would be 5g/7r instead ! Brilliant Member · 10 months, 1 week ago

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@Vighnesh Shenoy Thanks Rajdeep Dhingra · 1 year, 4 months ago

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Solution for Question 1:

Saarthak Marathe · 1 year, 4 months ago

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@Saarthak Marathe Thanks ! Rajdeep Dhingra · 1 year, 4 months ago

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@Rajdeep Dhingra You are welcome Saarthak Marathe · 1 year, 4 months ago

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