Chapter 4.4, Problem 50E

Wind Velocity Under certain geographic conditions, the wind velocity $v$ at a height $x$ centimeters above the ground is given by $v=K\ln \left(x/x_0\right)$, where $K$ is a positive constant (depending on the roughness of the vegetation on the ground). Suppose that $x_0=.7$ cm (a value that applies to lawn grass $3$ centimeters high) and $K=300$ centimeters per second. (Source: Dynamic Ecology)

a. At what height above the ground is the wind velocity zero?

b. At what height is the wind velocity $1200$ centimeters per second?