(Solved): 12) A 960m wide river flows at 16m/s as shown in the figure. Alice and John have a race in ide ...

12) A $960-\mathrm{m}$ wide river flows at $16\mathrm{m}/\mathrm{s}$ as shown in the figure. Alice and John have a race in identical boats which each travel $20\mathrm{m}/\mathrm{s}$ in still water. Alice leaves point $A$ and steers so that she goes straight to point $B$ directly across and then back to $A$. John leaves point $A$ and steers up to point $C$ ( $960\mathrm{m}$ upstream) and then returns to $A$. (a) Which person arrives back at point $\mathrm{A}$ first? (b) How much sooner than the loser does the winner arrive back at point A?