(a) Snow is falling vertically toward the ground at speed \(v\).

(a) A bus driver is driving through the snowstorm on a horizontal road at speed \(v / 3\). At what angle to the vertical are the snowflakes falling as seen by the driver?

(b) Suppose that the large windshield in the flat, vertical front of the bus has been knocked out, leaving a hole of area \(A\) in the vertical plane. Given that \(N\) is the number of falling snowflakes per unit horizontal area per unit time, if the bus moves at constant speed \(v / 3\) to reach a destination at distance \(d\), how many snowflakes fall into the bus before the destination is reached?

(c) To minimize the total number of snowflakes that fall in, the driver considers driving faster or slower. What would be the best speed to take?