For an outdoor lab experiment a car has a loud device attached to the roof. This device emits beeps with a pitch of 400 Hz. The device is set to constantly emit short beeps a rate of twice every second. The car drives at 25 m/s (About 55 mph) on a level track towards a student with a frequency meter. Which of the following correctly describes both the pitch of the individual beeps measured by the student and the rate that the student hears the beeps?
A. Pitch of each beep :The student measures each beeps pitch as lower than 400 Hz
Rate of Beeps:The student hears exactly 2 beeps per second
B. Pitch of each beep: The student measures each beeps pitch as higher than 400 Hz
Rate of Beeps : The student hears more than 2 beeps per second
C. Pitch of Each beep: the student measures each beeps pitch as exactly 400 Hz
Rate: The students hears more than 2 beeps per sec
D. The student measures each beeps pitch as higher than 400
Rate of beeps: student hears exactly 2 beeps per sec
The answer is B but can someone explain why that is true? I got this wrong on my test but I am doing corrections