A bag contains a mixture of copper and lead BBs. The average density of the BBs is 9.80g/cm^3.
Assuming that the copper and lead are pure, how does one determine the relative amounts of each kind of BB?
A bag contains a mixture of copper and lead BBs. The average density of the BBs is 9.80g/cm^3.
Assuming that the copper and lead are pure, how does one determine the relative amounts of each kind of BB?
Look up the densities of copper and lead from somewhere, and denote these by $\rho_c$ and $\rho_l$. Since we are interested in relative amount only, we can assume that the volume of BB's is altogether one unit, say $1 cm^3$, and split it into 2 parts: $x$ and $1-x$ (both in $cm^3$): $x$ is the volume of copper BB's, say.
So, considering the masses, denoting $\bar\rho$ the known average density: $x\cdot\rho_c +(1-x)\cdot\rho_l = 1\cdot\bar\rho$