The discussion focuses on calculating the speed of a car using the Doppler Effect, specifically when a policeman detects a 10% drop in the pitch of the car's horn as it passes by. The velocity of sound is given as 330 m/s. The relevant equation used is f2 = f1 [v - v(listener)]/[v - v(source)], where f2 represents the apparent frequency and f1 the true frequency. The solution involves understanding the transition of the car's motion from approaching to receding from the observer.
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Welcome to Physics Forums.Kinar said:Homework Statement
A policeman detects a drop of 10% in the pitch of the horn of a motor car as it crosses him. If the velocity of sound is 330ms^-1, calculate the speed of the car.
Homework Equations
f2 = f1 [v - v(listener)]/[v - v(source)]
where f2 = apparent frequency
f1 = true frequency
The Attempt at a Solution
I'm confused about how the car crosses him. Please help.