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Speed of Sound — Reading Comprehension

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MS-PS4-1
MS-PS4-2

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This comprehensive passage for grades 6-8 explores the science behind the speed of sound and how it varies depending on the medium—solid, liquid, or gas. Aligned with NGSS standards MS-PS4-1 and MS-PS4-2, the text delves into the mechanisms that determine how fast sound travels, using real-world phenomena like thunder and fireworks to anchor understanding. Students will learn that sound moves fastest in solids, slower in liquids, and slowest in gases due to particle arrangement. The passage also covers the impact of temperature on sound speed and connects the topic to broader scientific principles, such as energy transfer and wave behavior. The resource includes a glossary, quiz, writing prompts, and engaging graphic organizers. Audio integration makes this resource accessible for diverse learners and supports students in building both scientific and academic vocabulary.

CONTENT PREVIEW

Sound is a type of energy that travels in waves. When you see lightning during a storm, you often hear the thunder seconds later. This delay is caused by the speed at which sound travels from the lightning to your ears. Understanding the speed of sound helps scientists explain natural events and design better technology for communication.

What Determines the Speed of Sound?
The speed of sound does not depend on the sound itself, but rather on the medium through which it moves. A medium is any substance—solid, liquid, or gas—that sound waves can travel through. In solids, particles are packed closely together, allowing sound waves to move quickly from one particle to the next. In liquids, the particles are less tightly packed, so sound moves a bit slower. In gases like air, particles are spread far apart, making it harder for sound waves to travel. At room temperature, the speed of sound in air is about 343 meters per second (m/s), but in water it is around 1,480 m/s, and in steel it can be as high as 5,960 m/s. This difference is because sound waves need particles to transfer energy, and particles in solids are closer together than in liquids or gases.

How Temperature and Medium Affect Sound Speed
The speed of sound can also change with temperature. When air is warmer, its particles move faster and are slightly closer together, making it easier for sound waves to travel. For example, on a hot day, sound may travel faster than on a cold day. This explains why you may hear distant noises more clearly in summer. The relationship between medium, temperature, and sound speed is a key concept in physics. Some scientific instruments, like ultrasound machines, use high-frequency sound waves that move through different tissues in the body at different speeds to create images for doctors.

Examples and Real-World Applications
Everyday experiences show how sound speed varies. When you watch fireworks, you see the explosion before you hear the boom. This is because light travels much faster than sound. In weather forecasting, the time between seeing lightning and hearing thunder helps estimate how far away a storm is—every 3 seconds of delay means the storm is about 1 kilometer away. Engineers use the properties of sound speed to design buildings, concert halls, and even submarines, making sure that sound travels in controlled and useful ways.

Understanding the speed of sound connects to broader scientific principles, such as energy transfer and wave behavior. By studying how sound interacts with different materials and conditions, scientists and engineers can solve real-world problems and create new technologies.

Interesting Fact: Whales communicate with each other over hundreds of kilometers because sound travels much faster and farther in water than in air!

What is the primary factor that determines the speed of sound?

The medium through which sound travelsThe loudness of the soundThe color of the object producing soundThe size of the sound wave

Which state of matter allows sound to travel fastest?

SolidLiquidGasPlasma

At room temperature, what is the speed of sound in air?

343 meters per second1,480 meters per second5,960 meters per second100 meters per second

According to the passage, why do you see fireworks before you hear them?

Light travels much faster than soundSound is louder than lightTemperature affects light speedFireworks make no sound

What happens to the speed of sound as temperature increases?

It increasesIt decreasesIt stays the sameIt stops completely

In the context of the passage, what does 'medium' mean?

A substance that sound waves travel throughA tool used to measure soundA type of energyA temperature scale