Question

MATHEMATICS - X
5. What length of a solid cylinder 2 cm in diameter must be taken to recast into a hollow
cylinder of length 16 cm, external diameter 20 cm and thickness 2.5 mm?
5. A cylindrical vessel hay​

Answer 1

Answer:

74.60cm

Explanation:

Given diameter of solid cylinder is 2 cm.

Radius of solid cylinder, r=1 cm.

Volume of solid cylinder is πr  

2

h

=π×1  

2

×h=πh→(1)

Length of hollow cylinder, H=15 cm

External diameter =20 cm

External radius =10 cm

Thickness =0.25 cm

Internal radius =10–0.25=9.75 cm

Volume of hollow cylinder  =π[10  

2

–(9.75)  

2

]×15

=15π×19.75×0.25→(2)

From (1) and (2), we get

πh=15π×19.75×0.25

 

Hence, h=15×19.75×0.25=74.06 cm