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Find the centre of mass of a unifrom (a) half-disc,(b) quarter-disc.A. `(R,R/pi)`B. `0,0`C. `(4R/pi,0)`D. `(0,(4R)/(3pi))` |
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Answer» Correct Answer - D The half disc can be supposed to be consisting of a large number of semicircular rings of mass `dm` and thickness `de` and radii ranging from `r=0` to `r=R` `x_(CM)=1/mint_(0)^(R)xdm=1/mint_(0)^(R)0 dm=0` `y_(cm)=1/Mint_(0)^(R)ydm=1/Mint_(0)^(R)(2r)/mxx((2M)/(R^(2))rdr)=((4R)/(3pi))` Surface area of ring `=pirdr` `dm=(2M)/(R^(2))rdr` |
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