Answer
$a = 83.3~m/s^2$
Work Step by Step
We first convert the speed to units of m/s;
$v = (150~km/h)(\frac{1000~m}{1~km})(\frac{1~h}{3600~s}) = 41.67~m/s$
We can then find the acceleration of the air;
$a = \frac{v-v_0}{t} = \frac{41.67~m/s-0}{0.50~s}$
$a = 83.3~m/s^2$
