Please help!

Please help me in the 7th question....

#Mechanics

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Comments

@Spandan Senapati

A Former Brilliant Member - 4 years, 3 months 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.Ok

Spandan Senapati - 4 years, 3 months ago

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

Harsh Shrivastava - 4 years, 3 months ago

@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 - 4 years, 3 months ago

@Spandan Senapati – Yes irodovs questions are good they are good but they are repeated in many books.

Harsh Shrivastava - 4 years, 3 months ago

@Spandan Senapati – yes, i have done that book it's amazing.

A Former Brilliant Member - 4 years, 2 months ago

@A Former Brilliant Member – Complete??good.I just solve in leisure....

Spandan Senapati - 4 years, 2 months ago

@Spandan Senapati – nah, not completely though ;P

A Former Brilliant Member - 4 years, 2 months ago

@A Former Brilliant Member – I used to solve some each day before inpho but now I have made up a plan to complete It.

Spandan Senapati - 4 years, 2 months ago

@Spandan Senapati – nice , it's an awesome book , go for it.

A Former Brilliant Member - 4 years, 2 months ago

@A Former 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 - 4 years, 2 months ago

@Spandan Senapati – dekhunga abhi ke liye toh jee bhot h :P

A Former Brilliant Member - 4 years, 2 months ago

@A Former Brilliant Member – pdf h iskki ?

A Former Brilliant Member - 4 years, 2 months ago

@A Former Brilliant Member – No my sir had given me...Not now but do try after you go an iit

Spandan Senapati - 4 years, 2 months ago

@Spandan Senapati – Ya....that book is very good.

A Former Brilliant Member - 4 years, 2 months ago

@Spandan Senapati – yes sure , why not ? i'll be doing mechanics for next 3 days even though i have chem exam ;P

A Former Brilliant Member - 4 years, 2 months ago

@Harsh Shrivastava – Further you may try David morin and peter gnadig's book " 200 puzzling questions in physics"

A Former Brilliant Member - 4 years, 3 months ago

@A Former Brilliant Member – But answer to David Morin's questions are not available? Do u have them?

Harsh Shrivastava - 4 years, 3 months ago

@Harsh Shrivastava – I feel the questions in Problems section are good enough .These problems have detailed solution which should be enough I guess.

A Former Brilliant Member - 4 years, 3 months ago

I got it. Will post a solution by night.

Harsh Shrivastava - 4 years, 3 months ago

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 - 4 years, 3 months ago

Thanks Harsh & Spandan.

A Former Brilliant Member - 4 years, 3 months ago

Any suggestion on coordinate geometry, I am very weak in it?

Harsh Shrivastava - 4 years, 3 months ago

TMH and archive will suffice.

A Former Brilliant Member - 4 years, 3 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.

Spandan Senapati - 4 years, 2 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....

Spandan Senapati - 4 years, 2 months ago

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

Harsh Shrivastava - 4 years, 2 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 - 4 years, 2 months ago

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

Spandan Senapati - 4 years, 2 months ago

@Spandan Senapati – I just know how to apply it I don't know the technalities behind it, will study soon.

Harsh Shrivastava - 4 years, 2 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 $y^2=4ax$

Spandan Senapati - 4 years, 2 months ago

Yeah you are right, my mistake, edited!

Harsh Shrivastava - 4 years, 2 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 - 4 years, 2 months ago

Math	Appears as
Remember to wrap math in `\(` ... `\)` or `\[` ... `\]` to ensure proper formatting.
`2 \times 3`	$2 \times 3$
`2^{34}`	$2^{34}$
`a_{i-1}`	$a_{i-1}$
`\frac{2}{3}`	$\frac{2}{3}$
`\sqrt{2}`	$\sqrt{2}$
`\sum_{i=1}^3`	$\sum_{i=1}^3$
`\sin \theta`	$\sin \theta$
`\boxed{123}`	$\boxed{123}$