Question

5. A copper wire 4mm in diameter in evenly wound about a cylinder whose length is 24cm and diameter 20cm so as to cover the whole surface. Find the length and weight of the wire assuming the specific gravity to be 8.88gm/cm3​

Answer 1

SOLUTION

d=4mm=0.4cm

now number of wound=24/0.4=60

now...length of each wound

=20π cm

therefore..length of the wire

=(20π×60)cm=1200π cm

now....

the volume of the cylindrical wire of radius =04/2=0.2 cm and length=1200π cm is

$= \pi(0.2) {}^{2} \times 1200\pi \\ = 48\pi {}^{2} \: \: cm {}^{3}$

therefore weight of the wire....is ...

$48( \frac{22}{7} ) {}^{2} \times 8.88 \: \: gm \\ = 4210.207 \: \: gm \\ = 4.2 \: kg \: (almost)$