Answer
$1.5\times10^5K$
Work Step by Step
The rms speed is given by equation 13–9.
Use the equation, applied to nitrogen.
$$v_{rms}=\frac{42000000m}{3600s}=\sqrt{\frac{3kT}{m}}=\sqrt{\frac{3(1.38\times10^{-23}J/K)T}{28(1.66\times10^{-27}kg)}}$$
Solve for $T\approx1.5\times10^5K$.
