Question

A metal pipe has a bore(inner diameter) of 5 cm.The pipe is 5 mm thick all round.Find the weight,in kilogram,of 2 metres of the pipe if 1 cm³ of the metal weighs 7.7g.(Answer:13.31 kg)

Please answer this today only.I will mark your answer as brainliest if correct.

Answer 1

The inner diameter = 5cm
The inner radius = 5/2 = 2.5cm
The thickness = 5mm = 5/10 cm = 0.5cm

The outer radius = 2.5 + 0.5 = 3cm

The length of the pipe = 2m = 2x100cm = 200cm

Volume of the pipe = 22/7 x R² X h   22/7 x r² x h = 22/7 xh (R² - r²)
Where R= outer radius, r = inner radius and h = length of pipe


∴ Volume = 22/7 x 200 (3² - 2.5²)
                = 22/7 x 200 (9 - 6.25)
                = 1728.57 cm³
Mass = Density x Voulme
          = 7.7 x 1728.57
          = 13310g

1000g = 1kg
∴ the mass = 13310/1000 = 13.31 kg

Answer 2

The inner diameter = 5cm
The inner radius = 5/2 = 2.5cm
The thickness = 5mm = 5/10 cm = 0.5cm

The outer radius = 2.5 + 0.5 = 3cm

The length of the pipe = 2m = 2x100cm = 200cm

Volume of the pipe = 22/7 x R² X h   22/7 x r² x h = 22/7 xh (R² - r²)
Where R= outer radius, r = inner radius and h = length of pipe


∴ Volume = 22/7 x 200 (3² - 2.5²)
                = 22/7 x 200 (9 - 6.25)
                = 1728.57 cm³
Mass = Density x Voulme
          = 7.7 x 1728.57
          = 13310g

1000g = 1kg
∴ the mass = 13310/1000 =  13.31 kg