Question

A copper rod of diameter 1 cm and length 8 cm is drawn into a wire of length 18 m of uniform thickness.
Find the thickness of wire.
​

Answer 1

Answer:

The volume of the rod = π×(

2

1

)

2

×8=2π cm

3

The length of the new wire of the same volume = 18 m = 1800 cm

If r is the radius ( in cm ) of cross-section of the wire, its voume = π×r

2

×1800 cm

3

Therefore,

π×r

2

×1800=2π

r

2

=

900

1

r=

30

1

So, the diameter of the cross section, i.e., the thickness of the wire is

15

1

cm, i.e., 0.67 mm (approx.)