Per Class: tuning forks rubber mallet or the rubber bottom of a shoe resonance box optional. If using this as an activity, provide the materials above for each pair of students. Why do different sized tuning forks produce different sounds? If you know frequency of each fork, can you tell me how many times per second each fork will vibrate?
How can we increase the volume of a tuning fork? How can we decrease the volume of a tuning fork? Details Activity Length 10 mins.
In this activity, students experiment with tuning forks to produce various pitches and volumes. Hitting the fork harder will produce a louder sound because the initial vibration was larger. Both pitch and volume are subjective.
These words refer to what the listener experiences. Objectives Describe the properties of sound. Describe what pitch is and how it varies. By hitting a tuning fork, you're causing its tines to vibrate back and forth several hundred times per second. Often, the vibrations are so fast that they're not visible to the human eye.
If you need proof, simply dip a humming tuning fork into a cup of water -- it'll kick up a surprisingly large jet of water. In scientific terms, the speed of a tuning fork's vibrations is known as its frequency , a quantity measured in hertz Hz , or vibrations per second.
The way a tuning fork's vibrations interact with the surrounding air is what causes sound to form. When a tuning fork's tines are moving away from one another, it pushes surrounding air molecules together, forming small, high-pressure areas known as compressions. When the tines snap back toward each other, they suck surrounding air molecules apart, forming small, low-pressure areas known as rarefactions.
The result is a steady collection of rarefactions and compressions that, together, form a sound wave. The faster a tuning fork's frequency, the higher the pitch of the note it plays. For instance, for a tuning fork to mimic the top key on a piano, it needs to vibrate at 4, Hz. This activity explores how sound energy vibrations are transferred from the tuning fork to the ping-pong ball to make it move. For this experiment, students will build a simple drum to demonstrate the way sound causes vibrations.
Sound is an important physics concept that students will enjoy learning. And these tuning fork experiments are great visual examples of how vibrations cause sound waves. Continue learning with Exploring the Science of Sounds , which allows students to listen, experiment, and discuss different kinds of sounds and the tools for making them. Teach your students about the many genres of music and learn their favorites!
Specialized techniques were developed to use them for measuring different kinds of vibrations, and they were frequently used as high-precision timing standards. Albert Michelson, for example, used light reflected from the vibrating tines of a tuning fork to make his historic measurements of the speed of light. In the 20th century, the development of electronic technologies for measurement and precision timing quickly replaced technologies that employed mechanical tuning forks.
One notable exception has been the introduction, around , of tiny quartz tuning forks in high-precision watches. Maintained in motion by batteries, the resonating forks far exceed the accuracy of conventional mechanical watches. The tuning forks were each milled from a single blank of fine steel and were then precisely tuned to produce a single, specific, tone.
The resonator boxes that they are bolted to are wood, made from the same spruce often used in stringed musical instruments. Spruce wood is naturally responsive to sound vibrations and is the ideal material for this application.
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