The external diameter of the forepart of a bowl made of a copper plate of thickness 1 cm is 12 cm.If the weight of 1cc of copper be 12gm, then what will be the weight of the bowl ?

Explanation

The external radius of the semicircular bowl `=(12)/(2)` cm =6 cm.
The bowl is of thickenss 1 cm.
So, the internal radius of the bowl =(6-1)cm =5cm.
`:.` the volume of the material of the bowl
`=((2)/(3)pixx6^(3)-(2)/(3)pixx5^(3)) "cc" =(2)/(3)pi(216-125)"cc"=(2)/(3)xx(22)/(7)xx91` cc
`:.` the weight of the bowl `=(2)/(3)xx(22)/(7)xx91xx12` gm=2288 gm =2.288 kg.
Hence the weight of the demicircular bowl =2.288kg.