rotation

JUST WANT ANSWERS FOR VERIFICATION

For the system shown in figure find:
(a) the linear acceleration of hoop
(b) angular acceleration of hoop of mass M
(c) tension in the rope

masses are M and m and radius of hoop is r

8 Answers

49
Subhomoy Bakshi ·

hoping hoop means loop means a ring,

angular accn=α
linear accn=a
tension=T....
friction=f

asssuming pure rolling,

from fbd,
T.r-f.r=Iα=(1/2Mr2).(a/r)
or, T-f=Ma/2..............(i)
from translation of hoop,
T+f=Ma...............(ii)
adding (i) and (ii),
2T=3Ma/2
or, T=3Ma/4...........(iii)
also,
mg-T=2ma..................(iv)

adding (iv)&(iii),
mg=2ma+3Ma/4
or, a=4mg/8m+3M

α=a/r

andT=3Ma/4

put values to get answers.....

49
Subhomoy Bakshi ·

now check i hav edited it.......

49
Subhomoy Bakshi ·

koi toh dekho yaar.............am i right????should i hav considered friction or not???????????

49
Subhomoy Bakshi ·

koi toh ise dekho plzz..........

1
Philip Calvert ·

do we have to assume pure rolling ?

49
Subhomoy Bakshi ·

yes we hav to otherwise according to my small mind we wont find any relation b/w a and α

106
Asish Mahapatra ·

@ Subhomoy: Please recheck the values you have used for the acceleration of M and m

If lin acceleration of M is a
then lin. acceleration of m is 2a.

btw the values were given as M=1kg m=0.2kg and r=0.2m

can you provide the values pls .. my answers were not matching

@phillip: nothing mentioned so i think we can assume pure rolling

49
Subhomoy Bakshi ·

hey ashis now check out......put vales and get answer.....

n by da way if rotation interests you go to http://targetiit.com/iit-jee-forum/posts/rotation-instantaneous-centre-of-rotation-12434.html......its all rotating there

also this one....http://targetiit.com/iit-jee-forum/posts/cylinders-ki-tower-p-12443.html

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