18. A police radar operates on a frequency of 1GHz. What is the value of the frequency shift received by the police after the signal is reflected by a car moving away from the police at the velocity 150 km/hr?
(A) 278 Hz
(B) 2.78 kHz
(C) 27.8 kHz
(D) 278 kHz

(E) 2.78 MHz

答案:登入後查看
統計: 尚無統計資料