A solid lead ball of radius 7cm was melted and then drawn into a wire of diameter 0.2cm. Find the length of the wire.

Explanation

Radius of ball, `r=7cm`

Radius of wire, `R=0.2/2=0.1cm`

Volume of metal used in wire
=Volume of the lead ball

`piR^2h=4/3pir^3`

`0.1^2h=4/3xx7^3`

`0.01hxx3=4xx343`

`h=(4xx343)/(0.01xx3)`

...