A bicyclist rides along the hard-packed sand beach with a speed $v_{B}=16 \mathrm{mi} / \mathrm{hr}$ as indicated. The wind speed is $v_{w}=20 \mathrm{mi} / \mathrm{hr} .(a)$ Determine the velocity of the wind relative to the bicyclist.
(b) At what speed $v_{B}$ would the bicyclist feel the wind coming directly from her left (perpendicular to her path)? What would be this relative speed?