A delivery truck with \(2.8-\mathrm{m}\)-high aluminum sides is driving west at \(75 \mathrm{~km} / \mathrm{h}\) in a region where the earth's magnetic field is \(\vec{B}=\left(5.0 \times 10^{-5} \mathrm{~T}\right.\), north \()\)

a. What is the potential difference between the top and the bottom of the truck's side panels?

b. Will the tops of the panels be positive or negative relative to the bottoms?