I have this question: If the diesel engine coasts at 4.8 km/h into a freight car that is initially at rest, find the speed of the coupled cars. Now I'm looking at the work done, on the answers given but I'm not understanding where the 5.8 coming in to play?

Nacidified solution was electrolyzed using copper electrodes. a constant current of 1.18 a caused the anode to lose 0.584 g after 1.52 ✕ 103 s. given that the charge of an electron is 1.6022 ✕ 10−19 c, calculate avogadro's number. assume that copper is oxidized to cu2+ ions.