A long, rectangular loop of width $w$, mass $M$, and resistance $R$ is at rest, with the plane of the loop parallel to the ground. Immediately to the left of the loop is a region of uniform magnetic field $\vec{B}$ that points out of the screen. At time $t = 0$, a constant force $\vec{F}$ pushes the loop to the left, into the magnetic field region, as shown in the figure.
Derive an expression for the speed $v(t)$ of the loop immediately after it enters the magnetic field region in terms of given quantities and the time $t$.
