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A ball whose density is `0.4zxx1^(3) kg//m^(3)` falls into water from a height of 9 cm.To what depth does the balll sink?A. 9 cmB. 6 cmC. `4.5 cm`D. `2.25 cm` |
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Answer» The velocity of ball before entering the water surface `v=sqrt(2gh)=sqrt(2gxx9)` When ball enters into water, due to upthrust of water, the velocity of ball decreases (of retarded) The retardaion, `a=("apparent weight")/("mass of ball")` `(V(rho-sigma)g)/(Vrho)=((rho-sigma)g)/(rho)` `=((0.4)-1)/(0.4)g=-(3)/(2)g` If h be the depth upto which ball sin k, then `o-v^(2)=2xx((-3)/(2)g)xxh` `rArr " " 2g xx9=3gh` `:. " " h=6 cm ` |
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