Question

a copper rod of diameter 2 cm and length 10 cm is drawn into a wire of uniform thickness and length 10 m.Find the thickness of the wire

Answer 1

Given diameter of the copper rod = 1 cm

So, radius(r) of the copper rod = 1/2 cm

Let R is the radius of the cross section(circular) of the wire.

Now, according to the question,

      πR2 *(18*100) = π(1/2)2 *8

=> R2 *(18*100) = (1/2)2 *8

=> R2 *(18*100) = 8/4

=> R2 *(18*100) = 2

=> R2 = 2/(18*100)

=> R2 = 1/(9*100)

=> R = √{1/(9*100)}

=> R = 1/(3*10)

=> R = 1/30

Now, thickness of the wire = 2r = 2 * 1/30 = 2/30 = 1/15 = 0.067 cm

Answer 2

I'm sorry for the presentation....but hope it helps..