A bat traveling at a speed of 18.1 m/s sends out sound at a frequency of 48.2 kHz, can 'see' objects due to echolocation. What frequency would the bat hear returning from a stationary wall in front of it? (assume the speed of sound in air is 343 m/s)

(a) What frequency is received by a person watching an oncoming ambulance moving at 120 km/h and emitting a steady 853 Hz sound from its siren? The speed of sound on this day is 345 m/s. Hz (b) What frequency does she receive after the ambulance has passed? Hz

A bystander hears a siren vary in frequency from 590 Hz to 368 Hz as a fire truck approaches, passes by, and moves away on a straight street. What is the speed of the truck? (Take the speed of sound in air to be 343 m/s.)

Bats of the Vespertilionidae family detect the distance to an object by timing how long it takes for an emitted signal to reflect off the object and return. Typically they emit sound pulses 3.00 ms long and 70.0 ms apart while cruising. If an echo is heard 32.8 ms later (vsound = 331 m/s), how far away is the object? When an object is only 39.2 cm away, how long will it be before the echo is heard? When an object is only 39.2 cm away, the bat  __________   able to detect the echo.