a hollow cylindrical iron pipe with external and internal radii 8cm and 6cm respectively and length 35 cm is melted and recast into a solid wire of thickness 2.8 cm .find the length of wire.

Respuesta :

Answer:

[tex]500\ cm[/tex]

Step-by-step explanation:

step 1

Find the volume of hollow cylinder

[tex]V=\pi (r2^{2}-r1^{2})h[/tex]

we have

[tex]r2=8\ cm[/tex]

[tex]r1=6\ cm[/tex]

[tex]h=35\ cm[/tex]

substitute

[tex]V=\pi (8^{2}-6^{2})(35)[/tex]

[tex]V=\pi (28)(35)[/tex]

[tex]V=980\pi\ cm^{3}[/tex]

step 2

we know that

The wire is a solid cylinder with the same volume of the hollow cylinder

so

[tex]V=\pi r^{2}h[/tex]

we have

[tex]V=980\pi\ cm^{3}[/tex]

[tex]r=2.8/2=1.4\ cm[/tex] ----> the radius is half the diameter (thickness)

substitute and solve for h

[tex]980\pi=\pi (1.4)^{2}h[/tex]

[tex]980=(1.96)h[/tex]

[tex]h=980/(1.96)=500\ cm[/tex]