1ya and the title was because the answer makes it look quite easy..
and even the soln does but actually it isn't wen u havent got either of them
***edited **
sorry i forgot but i thought there was no need to verify rohans solution [1]
A steel ball with volume V is sinking with a speed of 'v' in a closed jar filled with honey.
what is the momentum of the honey if its density is Ï?
there actually was life bustling once in this thread but everyone (that includes only subhash and me) deleted their posts to make it fresh again!!
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4 Answers
1let us take the frame of reference at the bottom of the jar
observe that at each moment more of the honey is moving upward( because the ball is going downwards)
so momentum of honey = mdx/dt m=mass of honey=volume*Ï
and x is the distance of com of honey from the bottom
let the distance of the steel ball be l from the bottom
then for finding the centre of mass of honey we can consider it as a negative mass in this case x=(m+M)(L/2)-M(l)/(m+M-M)
we know as it is moving with constant velocity
Mg=ÏgV =>M=ÏV
dx/dt=-M/(m)dl/dt but dl/dt=-v
mdx/dt=mMv/(m)
=Mv
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