Question

A Cylindrical metal bar 50cm long and 6cm in diameter is pulled out to form a wire of diameter 3mm.
a. What length is the wire
b. How does the curved surface area of the wire Compare with that of the bar.

Answer 1

Answer:

Let the length be l

volume of wire= ¥(3/20)^2 x l

Volume of bar = ¥ x 3^2 x 50cm

Equate both volume

¥ x 9x/400 = ¥ x 9 x 50

cross multiply

¥9x = 400 x 9¥ x 50

x=20000 x 9¥/9¥

x =20000cm

20000cm = 200m

thus length = 200m