A rail gun accelerates a projectile from rest by using the magnetic force on a
current-carrying wire. The wire has radius \(r=5.1 \cdot 10^{-4} \mathrm{~m}\)
and is made of copper having a density of \(\rho=8960 \mathrm{~kg} /
\mathrm{m}^{3}\). The gun consists of rails of length \(L=1.0 \mathrm{~m}\) in a
constant magnetic field of magnitude \(B=2.0 \mathrm{~T}\) oriented
perpendicular to the plane defined by the rails. The wire forms an electrical
connection across the rails at one end of the rails. When triggered, a current
of \(1.00 \cdot 10^{4}\) A flows through the wire, which accelerates the wire
along the rails. Calculate the final speed of the wire as it leaves the rails.
(Neglect friction.)