Surface Area And Volume Test - 2

External radius = 7 + 1.5 = 8.5 cm
Internal radius = 7 cm.
Volume of iron = π × ((R × R) - (r × r))h = 22/7 × ((8.5 × 8.5) - (7 × 7)) × 42 = 3069 cm³
Mass of iron pipe = (3069 cm³ × 10 gm/cm³)
= 30690 gm
= 30.69 kg

Area of the wet surface = [2(lb + bh + lh) - lb] = 2(bh + lh) + lb = [2 (8 × 2.5 + 12 × 2.5) + 12 × 8] m² = 196 m²

Let the thickness of the bottom = x m
Then, volume = 18.096
(4 - 0.10) × (3 - 0.10) × (2 - 2x) = 18.096
2 - 2x = 1.6
x = 0.2
So, thickness of the bottom is 0.2 m.

As the rectangular sheet has been folded along its length, circumference of base of the cylinder = 2π × r = 44 cm and height of the cylinder = 20 cm.

Now, curved surface area of the cylinder = 2π × r × h = 44 × 20 = 880 cm²