Question

A solid is composed of a cylinder with hemispherical ends. If the total height of the solid is 105

cm and the radius of the hemispherical ends is 14 cm, find the cost of polishing the surface of the solid

at the rate of ₹ 0.1 per square cm.​

Answer 1

Answer:

Hemispherical part: r=7cm

Cylindrical part: r=7cm,h=104−(7+7)=90cm

Total surface area of the solid= CSA of cylindricall part+2×CSA of hemispherical part

=2πrh+2×2πr^2

=2πr(h+2r)

=2× 22 /7  ×7[90+2(7)]cm^2

=44×104cm^2

=4576cm  ^2

∴ TSA of the solid=4.576cm^2  

Cost of polishing at the rate of Rs.4 per 100cm^2

=4576× Rs.4 /100

=Rs.183.04

∴ Cost of polishing the solid=Rs.183.04.