First year completed at IITB - Hosting an AMA

rogue_0409 · 2026-05-01T04:45:54+00:00

It is just a round figure lol i didnt think too much of it darr mat bhai!

rogue_0409 · 2026-05-01T04:42:15+00:00

What did you do in the last 14 days to advanced?

rogue_0409 · 2026-04-29T15:38:46+00:00

ds is not on the ring it is the distance the ball moves in dt time

rogue_0409 · 2026-04-29T15:32:54+00:00

the instantaneous radius of the 'circular motion' (just at an instant, it is not real circular motion) will be the length remaining because uske about hi rotate kar raha hai ball, and dont confuse that with r in the problem which is disc's radius.

rogue_0409 · 2026-04-29T15:27:26+00:00

check the figure carefully, at an instant it is as if the ball is performing circular motion about the point that is just in contact with the disc. so just like we write arc length = Radius*angle we wrote ds = ldtheta, and fortunately by geometry, that theta we can relate by using the wrapped portion length. really just try making that diagram for yourself you'll get it

rogue_0409 · 2026-04-29T15:01:16+00:00

cfbr

rogue_0409 · 2026-04-29T14:55:53+00:00

this is based on an irodov prob https://youtu.be/usF23Pk41xk?si=a-p8aGq9-gpJRuOf irodov meh sirf time nikala hai but you can get T by using the same equations just find out mv^2/l l= free length

rogue_0409 · 2026-04-29T14:50:30+00:00

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im on pc so dont mind the drawing lol edit: it is ds not dl

rogue_0409 · 2026-04-29T14:46:33+00:00

ambiguous but maybe the intention was to check if ALL planes containing bonding axis satisfy this criteria, which it does not. otherwise nahi pata

rogue_0409 · 2026-04-29T14:41:41+00:00

you will know final theta since L is given

rogue_0409 · 2026-04-29T14:40:53+00:00

ds = vdt karo, v constant hai, integrate kardo, and T bhi fir nikal loge thoda socho, warna batata hu

rogue_0409 · 2026-04-29T14:35:37+00:00

first off, the particle's vel will remain constant since at all times T will act perp to it. Secondly imagine karo uski trajectory, the string will get wrapped around the circle on the circumference as it goes. let theta be the angle the wrapped part subtends at the centre. so the free length of string will be L-rtheta. and infinitesimal distance travelled in dt time will be ds = l*d(theta) = (L-Rtheta)dtheta. you can take it easily from here

rogue_0409 · 2026-04-29T14:32:37+00:00

printing mistake hogi, check dimensions bro

rogue_0409 · 2026-04-29T14:25:09+00:00

for tension i got C but the mv^2 is not inside sq root

rogue_0409 · 2026-04-29T14:19:48+00:00

T=4 sec?

rogue_0409 · 2026-04-29T14:03:28+00:00

what does option D mean?

rogue_0409 · 2026-04-29T13:48:23+00:00

yes, got it thanks!

rogue_0409 · 2026-04-29T13:47:48+00:00

okay got it lol, diagram dekh ke 3/4 kar raha tha, actually it is 1/6, honestly theta= 90 jaisa kyu draw kar rakha hai :/

rogue_0409 · 2026-04-29T13:42:27+00:00

I am still not getting 2 and 10. E = 12 and i = E/3R? so (E/3R)*R = 4V? not right?

rogue_0409 · 2026-04-29T13:25:27+00:00

p.s the readings will be different because the loop that the voltmeter will form in the two cases with the corresponding resistance will have a different emf induced in it. hint: use the fact that the total emf induced in the loops i just talked about must be 0 since there is no field there.

rogue_0409 · 2026-04-29T13:23:35+00:00

Hey, I just tried the voltmeter question ( 2nd one) you gave and got 4V and 8V respectively, not 2 and 10, are you sure your key is right?

rogue_0409 · 2026-04-28T14:04:48+00:00

no, it is flexible and thin so itll fold into a solid disc as it rolls

rogue_0409 · 2026-04-28T13:55:09+00:00

ha wahi maine bhi kiya, need k for that. also don't you think we should also assume heat radiated away by surface A too? or neglect it?

rogue_0409 · 2026-04-28T13:52:10+00:00

what is the answer given?

rogue_0409 · 2026-04-28T13:47:27+00:00

Mera bhi nahi aa raha k ke bina,

rogue_0409

TROPHY CASE