Make a "Coat Hanger Walkman"

Physics Volunteer Activities
Physics Volunteer Activities
Created by
Let's Talk Science National Office
Activity Language
English
Grade
Grades 1-3,  Grades 4-6,  Grades 7-8
Time Needed for Activity
Less than 1 hour
Subjects
Engineering,  Physics
Good for Virtual Delivery
No Consumables

Students explore the science of sound by creating their own "Walkman" which transmits vibrations through a piece of string.

What You Need

Coat Hanger Walkman:

  • 1 wire coat hanger per child
  • 1 piece of string, ~50 cm per child
  • 1 metal object per child - spoons and forks work well for this

If possible, pre-cut at least ~30 pieces (i.e., 1 class set) of string to make handing out materials quick and easy.

Optional Music Activity:

  • Three drinking glasses
  • Metal object
  • Water

Instructions:

What To Do

  1. Wind one end of a 50cm string around one finger several times.
  2. Wind the other end several times around a finger on your other hand
  3. Loop the string under the hook of a wire coat hanger
  4. Pick the coat hanger up by raising your hands. Place the fingers with the string on them into your ears.
  5. Have another person hit the coat hanger with your metal object, or lean over and bang the coat hanger against a table. Notice the sound. 
  6. Remove your fingers from your ears and bang the coat hanger again. 
  7. How has the sound changed? Why has it changed?

Discovery

Coat Hanger Walkman:
The tone of the metal object banging on the coat hanger is produced by the vibrations of the hanger. The sound waves are then transmitted to your eardrums by the string and your fingers. The sound is louder through the string than listening to the sound traveling through the air to your ears because the solid string transmits sound better than air. 

Optional Music Activity:
A sound is produced because of the vibrations of the glass. Water thickens the glass so that it vibrates slower. The change in pitch is due to the amount of water in each glass - a glass that is almost full of water produces lower pitched sounds, less water produces higher sounds.

To further explore the science of sound, you can add this additional activity. A more extensive version of this activity called "Make Your Own Bottled Music" can be found on the portal as well. 

Fill three or more glasses with different quantities of water.

  1. Hit the glasses with a metal object and notice the differences in sound.
  2. Try playing "Mary Had A Little Lamb" or "Twinkle Twinkle Little Star" with the glasses and spoon.

What's Happening?

Coat Hanger Walkman:
The tone of the metal object banging on the coat hanger is produced by the vibrations of the hanger. The sound waves are then transmitted to your eardrums by the string and your fingers. The sound is louder through the string than listening to the sound traveling through the air to your ears because the solid string transmits sound better than air. 

Optional Music Activity:
A sound is produced because of the vibrations of the glass. Water thickens the glass so that it vibrates slower. The change in pitch is due to the amount of water in each glass - a glass that is almost full of water produces lower pitched sounds, less water produces higher sounds.

Investigate Further

To further explore the science of sound, you can add this additional activity. A more extensive version of this activity called "Make Your Own Bottled Music" can be found on the portal as well. 

Fill three or more glasses with different quantities of water.

  1. Hit the glasses with a metal object and notice the differences in sound.
  2. Try playing "Mary Had A Little Lamb" or "Twinkle Twinkle Little Star" with the glasses and spoon.

Resources