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.

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 â€“ r

9 = R â€“ 27

R = 27 + 9

R = 36 cm

Now,

The volume of the iron sheet (V) = Ï€ Ã— (R2 âˆ’ r2) Ã— h

V = Ï€ Ã— (362 âˆ’ 272) Ã— 100

V = 1780.38 cm3

Hence, the volume of the iron sheet = 1780.38 cm3

Itâ€™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