Part 1: Story of the Racing Train
It was a sunny Saturday afternoon in the quaint town of Willow Creek, where the annual train festival was in full swing. Families gathered along the tracks to witness the spectacle of steam engines chugging along, their whistles piercing the air with jubilant sounds. Among the crowd was young Timmy, a train enthusiast with wide eyes and an insatiable curiosity. He positioned himself near the platform, clutching his small toy train, waiting eagerly for the grand arrival of the famous locomotive, "The Silver Comet."
As the sleek train approached, Timmy noticed the familiar whistle grow louder. He felt the ground tremble beneath his feet, and excitement bubbled up within him. Suddenly, the "Silver Comet" rounded a bend, and its whistle blared again, a magnificent sound that seemed to envelop him. Yet, as the train sped past, Timmy experienced something peculiar—the whistle shifted from a high-pitched wail to a lower tone in an instant. As the train zoomed away from him, the whistle faded into the distance, becoming barely a whisper before disappearing altogether. Intrigued, he turned to his father, who explained that this phenomenon, where the sound of the train's whistle changed as it moved towards and then away from them, was known as the Doppler effect.
Part 2: Explanation of the Doppler Effect
The Doppler effect refers to the change in frequency or wavelength of a wave in relation to an observer moving relative to the wave source. In Timmy's story, as the "Silver Comet" approached, the sound waves compressed, resulting in a higher frequency and a sharper whistle that became more intense. When the train passed by and moved away, the sound waves stretched out, leading to a lower frequency and a deeper sound. This shift in pitch, which captivated Timmy and sparked his keen interest in trains, beautifully demonstrated the Doppler effect in action.
1 answer