Find the length of 13.2 kg of copper wire of diameter 4 mm, when 1 cubic centimetre of copper weights 8.4 g.

Answer

125 m

Explanation

Let the required length of wire be x cm
Then, its volume `= ((22)/(7) xx (2)/(10) xx (2)/(10) xx x) cm^(3) = ((22x)/(175)) cm^(3)`
`:.` its weight `= ((22x)/(175) xx 8.4) g = ((22x xx 8.4)/(175 xx 1000)) kg`
`:. (22x xx 8.4)/(175 xx 1000) = 13.2`
`rArr x = ((13.2 xx 175 xx 1000)/(22 xx 8.4)) cm = ((132 xx 175 xx 1000)/(22 xx 84 xx 100))m = 125m`