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Make sci-fi sound effects with a slinky and a flowerpot!
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Curriculum links: KS2 Sound and Vibration, KS3 Waves, Sound
Download the experiment guide:
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You will need one metal slinky, one plastic flowerpot or cup, and duct tape.
You will need one metal slinky, one plastic flowerpot or cup, and duct tape.
- Hold the slinky at the top and let it extend down to the floor.
- Lift up a few coils so that they bunch together and release them. Or try gently striking the coils of slinky with a metal spoon.
- Listen to the sound made.
- Now tape the base of the flowerpot to the top coil of the slinky (the opening of the flowerpot should face away from the slinky).
- Holding the flowerpot so that the slinky extends down to the floor, lift and release or strike the coils as before.
- With the flowerpot attached, you will hear a loud chirping noise, like a laser sound effect from a sci-fi movie.
What is going on? Sounds occur when a vibrating object causes the surrounding medium (the stuff around it, such as air particles) to vibrate. The noise made by the slinky alone is tinny and quiet because the slinky has only a small vibrating surface area acting on the air around it.
The flowerpot has a large surface area and a large volume of air inside. The vibrations travel down the slinky, are reflected back up and reach the pot. The pot vibrates and causes the air inside and outside it to vibrate. The air in the pot vibrates, and the vibrations build up, making the sound much louder than with the slinky alone. This is called amplification.
Investigate further: Why the funny laser sound? The sound made by the slinky with the flowerpot starts high pitched and quickly drops to a lower pitch, giving it that distinctive "pew pew" noise, like a laser gun from a sci-fi movie.
The pitch of a sound depends on the frequency of the vibrations (how many vibrations occur every second). A high frequency vibration causes a high pitched sound, and a low frequency vibration causes a low pitched sound. In the case of the slinky, the vibrations do not all travel at the same speed. The higher frequency vibrations travel up the slinky faster than the lower frequency vibrations, so the high pitched sounds reach our ears first, then the low, causing that familiar drop in pitch.
The flowerpot has a large surface area and a large volume of air inside. The vibrations travel down the slinky, are reflected back up and reach the pot. The pot vibrates and causes the air inside and outside it to vibrate. The air in the pot vibrates, and the vibrations build up, making the sound much louder than with the slinky alone. This is called amplification.
Investigate further: Why the funny laser sound? The sound made by the slinky with the flowerpot starts high pitched and quickly drops to a lower pitch, giving it that distinctive "pew pew" noise, like a laser gun from a sci-fi movie.
The pitch of a sound depends on the frequency of the vibrations (how many vibrations occur every second). A high frequency vibration causes a high pitched sound, and a low frequency vibration causes a low pitched sound. In the case of the slinky, the vibrations do not all travel at the same speed. The higher frequency vibrations travel up the slinky faster than the lower frequency vibrations, so the high pitched sounds reach our ears first, then the low, causing that familiar drop in pitch.