the sound of 40 miles per hour

[asakiyume]

Wakanomori found a battered aluminum tuning fork in the road, not any old tuning fork: a police speed gun radar tuning fork, with 40 m.p.h. stamped on it.

Stationary speed radars work by shooting radio waves out at cars and then noting the frequency at which they bounce back. So this is the sound that equates to the frequency produced by waves traveling back after hitting a vehicle going 40 miles per hour.


It's the tune of a speed.

Movement sings.

Watch on YouTube

Comments

[sartorias]

Kind of a sweet ring.

[mallorys_camera]

I love this so much!!! 😀

[radiantfracture]

What an oddly beautiful thing to know about. Thank you.

[threemeninaboat]

That is amazing! I drive a Triumph Spitfire with a broken speedometer and can tell exactly how fast I am going by the engine sound :)

[oracne]

SO COOL! D#?

[amaebi]

:O

[sovay]

It's the tune of a speed.

That's marvelous.

[elusiveat]

That's wild. Thank you for sharing!

[minoanmiss]

This is so neat! Thank you once again for bringing us wonders.

[wayfaringwordhack]

What a marvelous find and marvelous thing to know. Oh the story possibilities!

[light_of_summer]

Yay, Physics!

I knew a little about Doppler effect in sound and astronomy, from school, but I don't think I knew its relationship to police radar.

You may already know this, but it looks to me like the tuning fork isn't actually used when the police measure someone's driving speed. It's used to check that the radar unit is correctly calibrated, which is supposed to be done at the start and end of every shift, so there won't be any reasonable doubts about measurement accuracy in related court cases.

Not as poetic, maybe, but certainly of interest!

[anna_wing]

A new thing learned today! How fascinating!

[lokifan]

Lovely!