3C
A bucket is tied to a string of mass M is lowered at a constant acceleration of g/4.If the mass of the bucket is M & is lowered by a distance d , the work done by the external agent on the string & bucket system will be ?
(A) Mgd/2 (B) - 3Mgd/2 (C) -3Mgd/4 (D) 3Mgd/2
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6 Answers
4@iitimcoming : The ans is - 3Mgd/2
I got 3Mgd/2
I had a doubt regarding the ' - ' ve sign
1Uttara can you please explain how the ans is -3Mgd/2. i got the - sign but how come magnitude is 3mgd/2
4Mg - T = Mg/4
T= 3Mg/4
For the system T1 = 2Mg - Mg/2 = 3Mg/2
So, W = - 3Mgd/2
[tension is acting in upward direction.....hence angle between force and distance is 180
fxdcos180=-fd ]
1tension is acting in upward direction.....hence angle between force and distance is 180
fxdcos180=-fd