Question

A police car is moving at 29 m/s is behind a speeding car moving faster in the same direction as the police car. The radar gun in the police car emits an 8 × 109 Hz electromagnetic wave. The frequency of the returning car wave is measured to be 318 Hz less than the emitted frequency. Find the speeders speed.

Answer 1

Answer:

z=(318/2) Hz / (8.0*10^9 Hz) = 2*10^(-8)

z=v/c

v=c*z = 3*10^8 m/s * 2 * 10^(-8) = 6 m/s

speedingcar has velocity 6m/s bigger then police car.

Hence, speeding car has velocity 29+6 = 35 m/s