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# A cylindrical road roller made of iron is 1 m long. Its internal diameter is 54 cm and the thickness of the iron sheet used in making roller is 9 cm. Find the mass of the road roller, if 1 cm3 of the iron has 7.8 gm mass.

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One of the important question for the board exam class 10 from
mensuration chapter.This question is from r d sharma class 10 maths.
chapter-16.2 question number-16 maths r d sharma,mensuration.

In this question we have to find the mass of the road roller, if 1 cm3
of the iron has 7.8 gm mass.A cylindrical road roller made of iron is
1 m long. Its internal diameter is 54 cm and the thickness of the iron
sheet used in making roller is 9 cm.

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1. Given,

Height/length of the cylindrical road roller = h = 1 m = 100 cm

Internal Diameter of the cylindrical road roller = 54 cm

So, the internal radius of the cylindrical road roller = 27 cm = r

Also given, the thickness of the road roller (T) = 9 cm

Let us assume that the outer radii of the cylindrical road roller be R.

T = R – r

9 = R – 27

R = 27 + 9

R = 36 cm

Now,

The volume of the iron sheet (V) = π × (R2 − r2) × h

V = π × (362 − 272) × 100

V = 1780.38 cm3

Hence, the volume of the iron sheet = 1780.38 cm3

It’s given that, mass of 1 cm3 of the iron sheet = 7.8 gm

So, the mass of 1780.38 cm3 of the iron sheet = 1388696.4gm = 1388.7 kg

Therefore, the mass of the road roller is 1388.7 kg

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