Doppler Effect and Sound Frequency

The video tutorial explains how to calculate the perceived pitch of sound using equations when a sound source, like a train, moves towards or away from an observer. It provides a scenario where a train approaches a crossing, emitting a siren at a known frequency. The tutorial demonstrates how to calculate the frequency heard by stationary pedestrians as the train approaches and then passes the crossing, using the speed of sound in air and the train's speed.

What is the primary factor that affects the pitch perceived by an observer when the source of sound is moving?

• The color of the sound source

• The speed of the sound source relative to the observer

• The size of the sound source

• The temperature of the environment

In the given scenario, what is the speed of the train as it approaches the pedestrians?

• 10 meters per second

• 15 meters per second

• 12 meters per second

• 20 meters per second

What is the frequency of the siren sound emitted by the train?

• 1,000 Hertz

• 1,050 Hertz

• 1,100 Hertz

• 950 Hertz

Which formula is used to calculate the frequency heard by the observer when the sound source is moving towards them?

• The formula where the emitter's speed is added to the wave's speed

• The formula where the wave's speed is doubled

• The formula where the emitter's speed is ignored

• The formula where the emitter's speed is subtracted from the wave's speed

What is the observed frequency when the train approaches the pedestrians?

• 1,000 Hertz

• 1,089.62 Hertz

• 1,050 Hertz

• 1,013.16 Hertz

When the train moves away from the observer, which formula is used to calculate the frequency heard?

• The formula where the two speeds are added

• The formula where the two speeds are subtracted

• The formula where the wave's speed is halved

• The formula where the emitter's speed is tripled

What is the speed of sound in air used in the calculations?

• 350 meters per second

• 330 meters per second

• 320 meters per second

• 300 meters per second

What is the observed frequency when the train moves away from the pedestrians?

• 1,013.16 Hertz

• 1,050 Hertz

• 1,089.62 Hertz

• 1,000 Hertz

Why does the frequency decrease when the train moves away from the observer?

• Because the waves bunch up

• Because the waves spread apart

• Because the waves change color

• Because the waves become louder

What is the effect on pitch when a sound-emitting object approaches an observer?

• The pitch remains the same

• The pitch increases

• The pitch becomes inaudible

• The pitch decreases