squanconsists of a cylinder of wood with a solid cylinder of graphite

1.	squanconsists of a cylinder of wood with a solid cylinder of graphite filled inThe diameter of the pencil is 7 mm and the diameter of the graphite is 1 mmof the pencil is 14 cm, find the volume of the wood and that of theIf the lengthgraphite.hosnital is given soup daily in a cylindrical bowl of diameter 7 cm. If the
Answer» Radius of graphite , r = 0.5mm = 0.05cmradius of wooden part of pencil, R = 3.5mm = 0.35cm length of pencil , l = 10cm now, volume of graphite = πr²l = π(0.05)² × 10 = π × 25 × 10^-3 cm³ weight of graphite = π × 25 × 10^-3 × 2.1 g [ mass = volume × density ] = 22/7 × 25 × 10^-3 × 2.1 g = 165 × 10^-3 = 0.165g volume of wooden part of pencil = π(R² - r²)l= π(0.35² - 0.05²) × 10= π(0.35 + 0.05)(0.35 - 0.05) × 10= π × 0.4 × 0.30 × 10 = π × 1.2 weight of wooden part , w = π × 1.2 × 0.7 = 22/7 × 1.2 × 0.7 = 2.64g so, total weight of pencil = 2.64g + 0.165g = 2.805g

squanconsists of a cylinder of wood with a solid cylinder of graphite filled inThe diameter of the pencil is 7 mm and the diameter of the graphite is 1 mmof the pencil is 14 cm, find the volume of the wood and that of theIf the lengthgraphite.hosnital is given soup daily in a cylindrical bowl of diameter 7 cm. If the

Answer»

Radius of graphite , r = 0.5mm = 0.05cmradius of wooden part of pencil, R = 3.5mm = 0.35cm length of pencil , l = 10cm

now, volume of graphite = πr²l = π(0.05)² × 10 = π × 25 × 10^-3 cm³

weight of graphite = π × 25 × 10^-3 × 2.1 g [ mass = volume × density ] = 22/7 × 25 × 10^-3 × 2.1 g = 165 × 10^-3 = 0.165g

volume of wooden part of pencil = π(R² - r²)l= π(0.35² - 0.05²) × 10= π(0.35 + 0.05)(0.35 - 0.05) × 10= π × 0.4 × 0.30 × 10 = π × 1.2

weight of wooden part , w = π × 1.2 × 0.7 = 22/7 × 1.2 × 0.7 = 2.64g

so, total weight of pencil = 2.64g + 0.165g = 2.805g