???

A small light pulley is attached with a block C of mass 4kg as shown. A block of mass 1.5kg is placed on the top horizontal surface of C. Another block A of mass 2 kg is hanging from a string, attached with B and passing over the pulley, system is released from rest. Accl of C is (g=10, nofriction)
1. 1.25
2. 1.5
3. 1.15
4.2.25

22 Answers

1
sriraghav ·

@ashis , In ur FBD for A pseudo force will b in LHS and not in upward dire....

1
sriraghav ·

1
sriraghav ·

K i'lll.....

11
Anirudh Narayanan ·

so, it is not that movement of A and B causes C to accelerate....it is quite the opposite.....movement of C causes movement of A and C???

106
Asish Mahapatra ·

[2][2] then i dunno..
can u post their solution?

1
sriraghav ·

no, ans is1.25

106
Asish Mahapatra ·

assume there is a force and solve.. if C acclerates towards right (say) then it will push A with it too.. So, A will exert a force on C.

11
Anirudh Narayanan ·

if the block is touching that face, then how ill there be a force??

106
Asish Mahapatra ·

11
Anirudh Narayanan ·

asish, what force causes C to move??

Can pls u explain giving a diagram??

106
Asish Mahapatra ·

i am doing everything from inertial frame... no pseudo forces.

11
Anirudh Narayanan ·

I don't think C will accelerate......what say you??

106
Asish Mahapatra ·

let the block C accelerate towards right with accn a.
Let acceleration of B wrt C be a1 towards left.. So actual acceleration of B is (a1-a) towards left.. acceleration of A in downward direction is a1.. the acceleration of A in horizontal direction is a.

Writing FBD of A.
2g-T=2a1 ... (i)
N(normal reaction by C) = 2a ... (ii)

FBD of B,
T=1.5(a1-a) ... (iii)

FBD of C along with pulley,
T-N = 4a ... (iv)

From (ii) and (iv) T=6a
and thus solving a=1.25

1
sriraghav ·

yes..... Hint: They hav used pseudo force, considering there is accl

11
Anirudh Narayanan ·

also there is no friction

11
Anirudh Narayanan ·

but i think all the forces on C act normally.... and nothing slong the sides

1
sriraghav ·

The string is horizontal and vertical in the figure...

1
sriraghav ·

no ani... u just hav to write FBD of all the blocks....

11
Anirudh Narayanan ·

11
Anirudh Narayanan ·

Then we nee d the angle which the ting which holds the pullley makes with C

1
sriraghav ·

It is YG file Q... I cudnt get the soln properly, so i want someone to explain clearly...

1
sriraghav ·

nope.. It luks lik dat ... but it will......

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