Final answer:
The frequency observed by the bus as it moves towards the police car can be calculated using the formula: f_b = f_s * (v + v_b)/(v - v_s)
Step-by-step explanation:
The Doppler effect can be used to determine the velocity of a moving object. In this case, the officer is using a doppler radar gun to measure the speed of the school bus. The frequency observed by the bus as it moves towards the police car can be calculated using the formula:
fb = fs * (v + vb)/(v - vs)
Where fb is the observed frequency, fs is the frequency emitted by the police car, vb is the velocity of the school bus, and vs is the velocity of the police car.