If the snowball takes 0.65 seconds to reach the smokestack, what is its velocity?
15 m
Smokestack
Knoll
* 4.5 m
Level ground
9.8 m/s
17 m/s
23 m/s
O 6.9 m/s

The ratio of lift to drag l/d for a wing or airfoil is an important aerodynamic parameter, indeed, it is a direct measure of the aerodynamic efficiency of the wing. if a wing is pitched through a range of angle of attack, l/d first increases, then goes through a maximum, and then decreases. consider an infinite wing with an naca 2412 airfoil. estimate the maximum value of l/d. assume that the reynolds number is 9x10^6.