Doppler Effect Concepts

How does the frequency of a sound wave change as the source approaches an observer?

If an observer is moving away from a stationary sound source, what will the observer notice about the sound?

What happens to the observed frequency of a sound as the source moves closer to the observer?

In Doppler ultrasound, what change is observed when blood cells are moving towards the probe?

What does a shift to a higher frequency in Doppler ultrasound indicate?

Two trains travel on parallel tracks in the same direction at 80 km/hr. What is the net movement between the two trains?

Two cars are moving along a straight road. Car A is moving north at 60 km/hr, and Car B, ahead of Car A, is moving north at 40 km/hr. What is the net movement between the two cars?

A bird flies south at a speed of 10 m/s, and a drone flies north at a speed of 15 m/s. What is their net movement relative to each other?

A police car is chasing a speeding car from behind. The police car’s siren emits a sound at a frequency of 1200 Hz. The police car is moving at 90 km/h, and the speeding car is moving at 110 km/h in the same direction. How does the driver of the speeding car perceive the siren’s sound?

Two cyclists, Alice and Bob, are riding side by side at a constant speed of 20 km/h and talking to each other. Alice speaks at a constant frequency of 200 Hz. How does Bob perceive Alice’s voice?