Question

The inner diameter of a hollow pipe made of metal is 5 cm and outer diameter is 7cm.
If 2 m pipe is melted and a wire of 2 mm diameter is formed from the metal,find the
length of the wire.​

Answer 1

The length of the wire made from melted metal of a pipe is 1200m

-The volume of the original pipe = pi.(r2^2 -r1^2).L

-here, r2 = 7cm/2 = 0.035 m

          r1 = 5cm/2 = 0.025 m

          L = 2 m

-Therefore we get total volume of metal melted = 3.77 * 10^-3 m^3

- dimensions of new wire made from this melted metal,

  L=?

  r=1mm = 10^-3 m

using the similar formula, V=pi.r^2.L

-Here L is unknown, so substituting V and r , we get L= 1200m