Question

find the volume od iron(in m3) used to make a one metre long cylindrical pipe having inner and outer radii of 70 cm and 77 cm respectively

Answer 1

r1 = 70cm
r2 = 77cm
h = 1m = 1000cm
Volume of hollow cylinder = πh(r2² - r1²)
By putting the values of r1, r2 and h, we get:
=> 3.14* 1000 * (77² - 70²)
=> 3140 * (5929 - 4900)
=> 3140 * 1029
=> 3231060 cm³
[1m³ = 1000000cm³]
so, 3231060 cm³ = 3231060/1000000
=> 3.23106 m³

Volume of pipe = 3.23 m³ (approx)
Hope the answer helps ( ͡ ͜ʖ ͡ )