Any suggestion on coordinate geometry, I am very weak in it?
–
Harsh Shrivastava
·
5 months, 1 week ago

Log in to reply

@Harsh Shrivastava
–
Hey you like integrals.I have a good one1)\(int1/(a+b(1-x))^2dx\)with x varying from \(0-1\).This is a Feynman's Puzzle.Looks easy but needs some more....
–
Spandan Senapati
·
5 months ago

Log in to reply

@Spandan Senapati
–
use the transformation x-> 1-x and then differentiate the function 1/(a+bx) wrt a and then done.
–
Harsh Shrivastava
·
5 months ago

Log in to reply

@Harsh Shrivastava
–
And also try to read "Feynman's trick"of differentiation under the integral sign.You will surely like it.
–
Spandan Senapati
·
5 months ago

@Harsh Shrivastava
–
OK ok.That will lead to answer of \(I=1/ab\).If a and b are of opposite sign then the integrals value is Negative \((ab<0)\).But the integrand be a square the area can never be negative.How do you resolve this...Here you integrating through Singularities.Pretty much the same thing as \(dx/x^2\) integral from (-1 to 1) isn't -2.The function blows up when x-->0...That's why its a Feynman's Puzzle...Try using limits in integrand.
–
Spandan Senapati
·
5 months ago

Log in to reply

@Harsh Shrivastava
–
Which part...I guess straight lines and circles you must be well acquainted with......Coordinate needs some heavy practice....Formulas and all those stuffs should be known all the time..?As such I don't follow any special book only fiitjee package.
–
Spandan Senapati
·
5 months ago

@Harsh Shrivastava
–
Hey in your q you talked abt Max area....I think it should be min.I did it as the req point of intersection is \(apq,a(p+q)\) where the points P and Q are \((ap^2,2ap)\)and \((aq^2,2aq)\).Then the cond yields \(apq=-1\).Vertex being \((0,0)\)The Area of \(PCQ\) is \(a^2|pq(p-q)|\).Puting \(pq=-1/a\) And later applying AM-GM yields the ans as \(Min=1\).\(a=1/4\) from \(y^2=4ax\)
–
Spandan Senapati
·
5 months ago

@Harsh Shrivastava
–
Ya I see the problem has been changed.Thanks....I was surprised because of the title "its right"....I accepted my ans to be wrong....
–
Spandan Senapati
·
5 months ago

Log in to reply

Use the fact that since we assume strings to be inextensible, velocity of M at bottommost point will be only in horizontal direction, and use constraint relation between the velocity of M and m by equating their velocities along the thread connecting them.Finally use energy conservation.
–
Harsh Shrivastava
·
5 months, 1 week ago

@A E
–
Ya I know this q.Follow Harsh s solution.And you will get it.And if any problem then tag me and I will post it.Ok
–
Spandan Senapati
·
5 months, 1 week ago

Log in to reply

@Spandan Senapati
–
Hey Spandan ,AE can you guyz tell me good source for practicing mechanics questions, especially rotational mechanics?
–
Harsh Shrivastava
·
5 months, 1 week ago

Log in to reply

@Harsh Shrivastava
–
Irodov(that's too good a book as I felt for rotational mech),and hc verma is good as well.For more tough prob you can refer to 300 creative physics problems by Laszlo Holics.
–
Spandan Senapati
·
5 months, 1 week ago

@Brilliant Member
–
Then try this "A guide to physics problems"... May be the second part be a bit tough as its Mostly Quantum Electrodynamics,Quantum Mechanics and all those stuffs but part 1 is good...... You will surely like it..And also try the integral I have posted
–
Spandan Senapati
·
5 months ago

@Harsh Shrivastava
–
Further you may try David morin and peter gnadig's book " 200 puzzling questions in physics"
–
A E
·
5 months, 1 week ago

Log in to reply

@A E
–
But answer to David Morin's questions are not available? Do u have them?
–
Harsh Shrivastava
·
5 months, 1 week ago

Log in to reply

@Harsh Shrivastava
–
I feel the questions in Problems section are good enough .These problems have detailed solution which should be enough I guess.
–
A E
·
5 months, 1 week ago

## Comments

Sort by:

TopNewestAny suggestion on coordinate geometry, I am very weak in it? – Harsh Shrivastava · 5 months, 1 week ago

Log in to reply

– Spandan Senapati · 5 months ago

Hey you like integrals.I have a good one1)\(int1/(a+b(1-x))^2dx\)with x varying from \(0-1\).This is a Feynman's Puzzle.Looks easy but needs some more....Log in to reply

– Harsh Shrivastava · 5 months ago

use the transformation x-> 1-x and then differentiate the function 1/(a+bx) wrt a and then done.Log in to reply

– Spandan Senapati · 5 months ago

And also try to read "Feynman's trick"of differentiation under the integral sign.You will surely like it.Log in to reply

– Harsh Shrivastava · 5 months ago

I just know how to apply it I don't know the technalities behind it, will study soon.Log in to reply

– Spandan Senapati · 5 months ago

OK ok.That will lead to answer of \(I=1/ab\).If a and b are of opposite sign then the integrals value is Negative \((ab<0)\).But the integrand be a square the area can never be negative.How do you resolve this...Here you integrating through Singularities.Pretty much the same thing as \(dx/x^2\) integral from (-1 to 1) isn't -2.The function blows up when x-->0...That's why its a Feynman's Puzzle...Try using limits in integrand.Log in to reply

– Spandan Senapati · 5 months ago

Which part...I guess straight lines and circles you must be well acquainted with......Coordinate needs some heavy practice....Formulas and all those stuffs should be known all the time..?As such I don't follow any special book only fiitjee package.Log in to reply

– A E · 5 months, 1 week ago

TMH and archive will suffice.Log in to reply

– Spandan Senapati · 5 months ago

Hey in your q you talked abt Max area....I think it should be min.I did it as the req point of intersection is \(apq,a(p+q)\) where the points P and Q are \((ap^2,2ap)\)and \((aq^2,2aq)\).Then the cond yields \(apq=-1\).Vertex being \((0,0)\)The Area of \(PCQ\) is \(a^2|pq(p-q)|\).Puting \(pq=-1/a\) And later applying AM-GM yields the ans as \(Min=1\).\(a=1/4\) from \(y^2=4ax\)Log in to reply

– Harsh Shrivastava · 5 months ago

Yeah you are right, my mistake, edited!Log in to reply

– Spandan Senapati · 5 months ago

Ya I see the problem has been changed.Thanks....I was surprised because of the title "its right"....I accepted my ans to be wrong....Log in to reply

Use the fact that since we assume strings to be inextensible, velocity of M at bottommost point will be only in horizontal direction, and use constraint relation between the velocity of M and m by equating their velocities along the thread connecting them.Finally use energy conservation. – Harsh Shrivastava · 5 months, 1 week ago

Log in to reply

– A E · 5 months, 1 week ago

Thanks Harsh & Spandan.Log in to reply

I got it. Will post a solution by night. – Harsh Shrivastava · 5 months, 1 week ago

Log in to reply

@Spandan Senapati – A E · 5 months, 1 week ago

Log in to reply

– Spandan Senapati · 5 months, 1 week ago

Ya I know this q.Follow Harsh s solution.And you will get it.And if any problem then tag me and I will post it.OkLog in to reply

– Harsh Shrivastava · 5 months, 1 week ago

Hey Spandan ,AE can you guyz tell me good source for practicing mechanics questions, especially rotational mechanics?Log in to reply

– Spandan Senapati · 5 months, 1 week ago

Irodov(that's too good a book as I felt for rotational mech),and hc verma is good as well.For more tough prob you can refer to 300 creative physics problems by Laszlo Holics.Log in to reply

– Brilliant Member · 5 months ago

yes, i have done that book it's amazing.Log in to reply

– Spandan Senapati · 5 months ago

Then try this "A guide to physics problems"... May be the second part be a bit tough as its Mostly Quantum Electrodynamics,Quantum Mechanics and all those stuffs but part 1 is good...... You will surely like it..And also try the integral I have postedLog in to reply

– Brilliant Member · 5 months ago

dekhunga abhi ke liye toh jee bhot h :PLog in to reply

– Brilliant Member · 5 months ago

pdf h iskki ?Log in to reply

– Spandan Senapati · 5 months ago

No my sir had given me...Not now but do try after you go an iitLog in to reply

– Brilliant Member · 5 months ago

yes sure , why not ? i'll be doing mechanics for next 3 days even though i have chem exam ;PLog in to reply

– A E · 5 months ago

Ya....that book is very good.Log in to reply

– Spandan Senapati · 5 months ago

Complete??good.I just solve in leisure....Log in to reply

– Brilliant Member · 5 months ago

nah, not completely though ;PLog in to reply

– Spandan Senapati · 5 months ago

I used to solve some each day before inpho but now I have made up a plan to complete It.Log in to reply

– Brilliant Member · 5 months ago

nice , it's an awesome book , go for it.Log in to reply

– Harsh Shrivastava · 5 months, 1 week ago

Yes irodovs questions are good they are good but they are repeated in many books.Log in to reply

– A E · 5 months, 1 week ago

Further you may try David morin and peter gnadig's book " 200 puzzling questions in physics"Log in to reply

– Harsh Shrivastava · 5 months, 1 week ago

But answer to David Morin's questions are not available? Do u have them?Log in to reply

– A E · 5 months, 1 week ago

I feel the questions in Problems section are good enough .These problems have detailed solution which should be enough I guess.Log in to reply