Question

A solid is composed by acylindrical with hemispherical ends.if the whole length of solid is 140cm and radius of each hemispherical is 7cm,find the cost of pollishing its surface at the rate of rupees 10 per unit?​

Answer 1

Answer:

Step-by-step explanation:

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×  

7

22

​  

×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×  

100

Rs.4

​  

=Rs.183.04

∴ Cost of polishing the solid=Rs.183.04.