$3.)$ Iron $($r$=0\mathrm{.}124$nm$,$ G$=70$ GPa$)$ is deformed to a shear strain of $0\mathrm{.}3.$ A dislocation density equal to $10^10$cm$^-2$ results. What is the average distance each dislocation had to move $($assume k$=1)?($b$)$ Assuming that the strain rate is $10^-2/$ s$,$ what is the average dislocation velocity?