Why you can hear a train on the railway tracks from miles away

The video explains how to detect an approaching train by listening to the sound waves traveling through railway tracks. It discusses the nature of sound as a pressure wave and how it propagates faster in solids than in gases due to molecular density. The video also covers the concept of sound intensity in different dimensions, highlighting why sound on tracks remains detectable over long distances. It concludes with safety advice and a call to support the channel.

Why does sound travel faster in solids compared to gases?

• Solids have more molecules that are closely packed.

• Gases have more molecules that are closely packed.

• Solids have fewer molecules that are widely spaced.

• Gases have fewer molecules that are widely spaced.

What is the speed of sound in air?

• 343 meters per second

• 1,482 meters per second

• 6,000 meters per second

• 70 meters per second

What is the primary reason you can hear a train from far away by placing your ear on the tracks?

• Sound intensity does not decrease in one-dimensional propagation.

• Sound waves are not absorbed by the tracks.

• Sound travels faster in air than in steel.

• Sound waves are amplified by the tracks.

How does sound intensity change in three-dimensional propagation?

• It remains constant.

• It increases by 1 over r squared.

• It decreases by 1 over r.

• It decreases by 1 over r squared.

What is the inverse square law related to?

• The speed of sound in different mediums.

• The increase of sound intensity in one dimension.

• The speed of trains on tracks.

• The decrease of sound intensity in three dimensions.