An important news announcement is transmitted by radio waves...

Name: Problem 62, Chapter 21: College Physics
Uploaded: 2019-11-16T18:43:28-08:00
Duration: 1 min 46 s
Channel: Averell Hause
Description: An important news announcement is transmitted by radio waves to people who are 100. km away, sitting next to their radios, and by sound waves to people sitting across the news- room, 3.0 m from the newscaster. Who receives the news first? Explain. Take the speed of sound in air to be 343 m/s.

An important news announcement is transmitted by radio waves to people who are 100. km away, sitting next to their radios, and by sound waves to people sitting across the news- room, 3.0 m from the newscaster. Who receives the news first? Explain. Take the speed of sound in air to be 343 m/s.

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Key Concepts

Electromagnetic Waves

Electromagnetic waves, such as radio waves, travel at the speed of light (approximately 3×10^8 m/s). This extremely high speed means that signals transmitted over vast distances, like 100 km, experience negligible delay, leading to almost instantaneous reception relative to slower wave types.

Speed of Sound

The speed of sound in air, given as 343 m/s, is much slower than the speed of light. This finite speed means that sound takes a measurable amount of time to travel even short distances. In practical applications, this delay is noticeable in scenarios where timing is critical, such as live announcements in a room.

Propagation Delay

Propagation delay is the time taken for a signal to travel from the source to the receiver. It depends on the distance between them and the speed at which the signal travels. Thus, a signal carried by radio waves will have an almost immediate arrival compared to a sound signal, which is delayed by the relative slowness of sound in air.

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