A cube of metal side is 7cm melted down and recast in a cylindrical mould with a diameter of 3cm. How long is the cylinder of metal?
The volume of the cube = (7cm)^3 = 343cm^3
Therefore, the cylinder has the same volume (assuming no loss due to melting)...so we have
343 = pi*r^2 *h →
343 =pi*(1.5)^2*h →
343 / [pi *(1.5)^2] = h = about 48.52cm