IIT JEE , AIEEE Forum - Physics , Mechanics

elastiboysai

2 forces F1 and F2 are applied on a spool (placed on a rough floor)of mass M and moment of inertia

I about an axis passin thru its centre of mass.

Find F1/F2 such that force of friction =0.

Given I<2MR^2 .

also gimme sum tips on how 2 solve such sums

I am bad at it

rooney

Hi

If no friction is acting, we can use I x Alpha = Net torque
I Alpha = 2F₁r- F₁
Also, F₁ + F₂ = MA
Alpha=A/2r
I= Moment of inertia of outer cylinder - Moment of inertia of inner cylinder = 3/2 Mr²
Combine these equations to get F₁/F₂= 7 : 5

elastiboysai

Rooney

the ans involves I.

.

can u plz solve in terms of I.

also dis is not a cylinder this is a spool.

Also y have dey gvn I<2MR^2.

rooney

Then do not replace I = 3mrsquare.

And solve using 1st three equations only.

elastiboysai

ok got it now

thanx

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