A lead pencil consists of a cylinder of wood | vedclass

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(D) Given that,$10 \,mm = 1 \,cm$,so $1 \,mm = 0.1 \,cm$.For the graphite cylinder:Diameter $= 1 \,mm = 0.1 \,cm$.Radius $(r) = \frac{0.1}{2} \,cm = 0

Vedclass · Accepted Answer

$5.28$

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(D) Given that,$10 \,mm = 1 \,cm$,so $1 \,mm = 0.1 \,cm$.For the graphite cylinder:Diameter $= 1 \,mm = 0.1 \,cm$.Radius $(r) = \frac{0.1}{2} \,cm = 0.05 \,cm$.Length $(h) = 14 \,cm$.Volume of graphite $= \pi r^2 h = \frac{22}{7} 	imes (0.05)^2 	imes 14 \,cm^3 = 22 	imes 0.0025 	imes 2 \,cm^3 = 0.11 \,cm^3$.For the pencil:Diameter $= 7 \,mm = 0.7 \,cm$.Radius $(R) = \frac{0.7}{2} \,cm = 0.35 \,cm$.Length $(h) = 14 \,cm$.Volume of pencil $= \pi R^2 h = \frac{22}{7} 	imes (0.35)^2 	imes 14 \,cm^3 = 22 	imes 0.1225 	imes 2 \,cm^3 = 5.39 \,cm^3$.Volume of wood = Volume of pencil - Volume of graphite$= 5.39 \,cm^3 - 0.11 \,cm^3 = 5.28 \,cm^3$.Thus,the volume of the graphite is $0.11 \,cm^3$ and the volume of the wood is $5.28 \,cm^3$.

$A$ lead pencil consists of a cylinder of wood with a solid cylinder of graphite filled in the interior. The diameter of the pencil is $7 \,mm$ and the diameter of the graphite is $1 \,mm$. If the length of the pencil is $14 \,cm$,find the volume of the wood and that of the graphite. (in $,cm^3$)

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