Question

20. A cylindrical roller made of iron is 2 m long. Its inner diameter is 35 cm and the thickness
is 7 cm all round. Find the weight of the roller in kg, if 1 cm of iron weighs 8 g.
17​

Answer 1

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Volume of cylindrical roller = πh(R²−r²)

Where R is outer radius and r is inner radius.

 

Given:

R = 21 cms

r = 17.5 cms

h = 200 cms

V = π200(21²−17.5²)

V = 84623cm³

 

Given 1cm³ of iron weights 8 g.

Then, total weight of the roller

= 84623×8

= 676984gms

= 676.984kg

 

Therefore, the weight of the roller is 676.98kg