Find the weight of led pipe is 3.5 m long if the external diameter of pipe is 2.4 cm and the thickness of led is 2mm and 1cm cube of the leg width is 4g

Answer 1

that's "lead" not led.

The area of a disc of diameter d is pi/4 d^2.

So, the area of the lead cross-section is

pi/4 (2.4^2 - 2.2^2) = 0.723 cm^2

So, the mass of the lead is volume * density, or

0.723cm^2 * 350cm * 4g/cm^3 = 1012.2g