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a cylinder of mass 10g weights 7g in water.if the area of crosssection is 0.75square its length will be..
 
 
 
Asked by ujjwalviky2003 | 02 Nov, 2017, 07:13: PM
answered-by-expert Expert Answer
area of crosssection is given as "0.75 square". we assume it is 0.75 square cm. 
wiht this assumption the answer is given below
 
As per law of floatation , weight of solid when it is fully immersed in water is given by
 
begin mathsize 12px style V open parentheses rho subscript s minus rho subscript w close parentheses g space equals space w e i g h t space m e a s u r e d space i n space w a t e r end style
V is volume, ρ is density( s for solid, w for water).

begin mathsize 12px style T h e space B o y a n c y space f o r c e space i s space V rho subscript w g space equals space V rho subscript s g space minus space left parenthesis W e i g h t space M e a s u r e d space i n space w a t e r right parenthesis V rho subscript w g space equals space left parenthesis 10 space minus space 7 right parenthesis g space sin c e space V rho subscript s g space w e i g h t space m e a s u r e d space i n space a i r space g i v e n space a s space 10 g sin c e space rho subscript w space equals space 1 space comma space w e space g e t space V o l u m e space a s space 3 space c m cubed end style
When volume is divided by crosssection, we can get length.
 
If that is done we can get the length as 4 cm
Answered by | 13 Dec, 2017, 07:34: PM

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