Question

A police car chases a speeder along a straight road towards a cliff both vehicles move at 160km/h the siren on the police car produces sound at a frequency of 100hz calculate Doppler shift in the frequency heard by the driver in a car behind the police at 120km/h moving towards the cliff and velocity if sound in air is 330m/s

Answer 1

Answer:

f ’= 97.0 Hz

Explanation:

This is an exercise of the doppler effect use the frequency change due to the relative movement of the fort and the observer

in this case the source is the police cases that go to vs = 160 km / h

and the observer is vo = 120 km / h

the relationship of the doppler effect is

          f ’= f₀ (v + v₀ / v- $v_{s}$)

let's reduce the magnitude to the SI system

            v_{s} = 160 km / h (1000 m / 1km) (1h / 3600s) = 44.44 m / s

            v₀ = 120 km / h (1000m / 1km) (1h / 3600s) = 33.33 m / s

we substitute in the equation of the Doppler effect

          f ‘= 100 (330+ 33.33 / 330-44.44)

          f ’= 97.0 Hz