A police car is traveling east at 40.0 m/s along a straight road, overtaking a car ahead of it moving east at 30.0 m/s. The police car has a malfunctioning siren that is stuck at 1 000 Hz.
(a) What would be the wavelength in air of the siren sound if the police car were at rest?
(b) What is the wavelength in front of the police car?
(c) What is it behind the police car?
(d) What is the frequency heard by the driver being chased?