Question

The thikness of a metallic tube is 1 cm and the inner diameter of the tube is 12 cm. Find the weight of 1 m long tube, if the density of the metal be 7.8 g/cm³.
Plzzz give me full answer

Answer 1

Inner diameter = 12 cm
Therefore, radius = 6 cm
Thickness = 1 cm
External radius = thickness + inner radius
=1 + 6 = 7 cm.
Length of tube = 1 m = 100 cm
Now, volume of tube = π(R² - r²)h
22/7 * (7² - 6²) * 100
22/7 * 13 * 100 = 4085.71 cm³
Density of metal per cm³ = 7.8 g
Weight of tube = 7.8 g × 4085.71 = 31868.538 g = 31.868 kg.

Answer 2

Inner Diameter = 12cm

Thickness = 1cm

Inner radius = 12/2 = 6cm

Outer radius = 6 + 1 = 7cm

Height 1 m = 100cm

Volume of metal = π (R²-r²) h

= 22/7 ( 7²-6² ) 100

= 22/7 (49-36 ) 100

= 22/7 ( 13 ) 100

= 22/7 * 1300

= 28600/7 cm³

Thus, 7.8 g/ cm³ = 28600/7 * 7.8

= 31868.57 g

= 1000g = 1 kg

In kg, 31868.57/1000

= 31.868 kg or 31.869 kg ( approx)