(Solved): You've decided to make a magnetic projectile launcher shown in the figure for your science project ...

You've decided to make a magnetic projectile launcher shown in the figure for your science project. An aluminum bar of length $l$ slides along metal rails through a magnetic The bar reaches a terminal speed $v_{\text{term. }}$. Find an expression for $v_{\text{term. }}$. field $B$. The switch closes at $t=0\mathrm{s}$, while the bar is at Express your answer in terms of ${\mathcal{E}}_{\text{bat }}$ (not the Greek letter epsilon ${?}_{\text{bat }}$ ), $B$, and $l$. rest, and a battery of emf ${\mathcal{E}}_{\text{bat }}$ starts a current flowing around the loop. The battery has internal resistance $r$. The resistance of the rails and the bar are effectively zero. (Figure 1) Figure $1\text{ of }1>\text{ Part B }$ Evaluate $v_{\text{term }}$ for ${\mathcal{E}}_{\text{bat }}=3.0\mathrm{V},r=0.10?,l=8\mathrm{cm}$, and $B=0.50\mathrm{T}$. Express your answer to two significant figures and include the appropriate units.