mechanics gems

do them if u feel to do .. syllabus blabla bla math lao yaha

1]Two beads of mass m are positioned at the top of a frictionless hoop of mass M andradius R, which stands vertically on the ground. The beads are given tiny kicks,and they slide down the hoop, one to the right and one to the left, as shown. Whatis the smallest value of m/M for which the hoop will rise up off the ground at some
time during the motion?

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25 Answers

3
iitimcomin ·

SO ZERO NA AS m>>M .....[OR IS IT DAT U SHUDNT TAKE DAT APPROX]

YAAR ITNA ACHHA KYSA TYPE KARTA HAI TU...................KOI SOFTWARE HAI KYA??????

1
chetan wahi ·

sorry everyone.

But I was frustrated with his questions.
I come here but dont post any questions .. but when i saw his question and that the is saying that he is typing all the question i really became angry.

62
Lokesh Verma ·

@chetan..

Dont get so emotional.
Sometimes you should oversee some of these things.
I think he was only trying to give some good questions.

62
Lokesh Verma ·

take it easy guys..

ltes forget this one..

I will try to get all the questions that he had posted.

Good atleast that we have the source of all those questions :)

3
iitimcomin ·

LUKS LIKE HES ALREADYT LEFT..... SAD I THINK HE MUST HAVE GOT OFFENDED .....

EVERY 1 MAKES SUM MISTAKES..... U SHUDA LEFT HIM ....

1
Philip Calvert ·

er..... well lets be a little easy on him chetan

maybe he gave it from other sources..... but that does not imply he was a fool... btw the problems are really good na ? so wats the problem and he is not forcing everyone to solve 'em ..

39
Dr.House ·

tahts why i said i gove it from sources. i never said i make them.

3
iitimcomin ·

WOHH... I DIDNT XPECT DAT FRM U MATHIE ............

3
iitimcomin ·

WAT ABT , 4TH 1 ????

AND THIRD 1 PLS SEE MAH METHOD ... I DUNNO HOW TO FIND LIMIT OF DAT 1......

3
iitimcomin ·

PLS SEE IF MAH SOLN. ARE RITE NA PLEASE.........

1
chetan wahi ·

okie..

and the solutions?

please tell na?

3
iitimcomin ·

frm where did u get these questions?????

3
iitimcomin ·

and the root and all dat???

106
Asish Mahapatra ·

Q1. 1/12 ??

3
iitimcomin ·

ar u sure we hav to assume M>>m .... then cum wat may the velocity of the big block will not change(wil be minute change) ...

and it will hit the wall..........

but if we apply COR/NLC and COM well see that the velocity of the ball after collision 1 is 2v0 .....

AFTER COLLISION 2 IT WILL REMAIN WITH THE BLOCK ITSEF AS IT WILL ASO HAVE VELOCITY V0 ...............SO NO MORE COLLISIONS AFTER THAT AND IT WILL HIT THE WALL.....

IVE GONE TERRIBLY RONG I TINK ......

OR IVE DONE TOO MUCH APPROX. WITH M>>m....

3
iitimcomin ·

3
iitimcomin ·

and the cookie i feel will be semicircular in 1 half and elliptical[not exactly but sumwat elliptical] in the other!!!!!![3].............

3
iitimcomin ·

Q4..might be rong....just my intution........

3
iitimcomin ·

6 B

3
iitimcomin ·

6 A ........ mgL/2 = 1/2 mv2 ................

√gL = v!!!!!!!!!!!

106
Asish Mahapatra ·

Q1.
From FBD of m,.... let speed be v when it makes angle θ with vertical.
Using WE theorem,
mv2/2 = mgR(1-cosθ) .....
==> v2 = 2gR(1-cosθ) ...... (i)

Writing force equation along normal,
mgcosθ - N = mv2/R
==> N = mg(3cosθ-2) ...... (ii)

If the mass M just lifts up,
then resulting force on it must be equal to Mg upwards.
Writing force equation along vertical for mass M,
Mg = 2Ncosθ
==> Mg = 2mg(3cosθ-2)cosθ
==> m/M = 1/2(3cos2θ - 2cosθ) ..... (iii)

For m/M to be min. d(m/M)/dθ = 0
==> taking derivative and solving,
cosθ=1/3

==> from (iii), m/M = 3/2

106
Asish Mahapatra ·

first one is 3/2

1
Indraneel Chatterjee ·

the first 1 is 1:2?

9
Celestine preetham ·

2) circular

3
iitimcomin ·

thanx dud for postin problem .........my bad luck i have to go now to study....hav comp. xam tommorow .... havnt started doin any thing!!!!!!
will attempt tommorow

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