Device (any similarity with real world intended)

[michel123456]

So I had a thought about the following device:

 

It is a shell of circular shape (A) with a small opening (B) and a small receptor C. The shell is rotating clockwise from Time 1 to Time 2.

 

For the sake of the argument, the shell is made of steel and the receptor is a stone-receptor. For simplicity the stones follow always a straight path.

The shell "understands" a stone only when it hits the receptor. If a stone enters the shell but does not hit the receptor, nothing happens. When a stone hits the receptor, bingo, a bell rings.

 

So I am at point D and I have to throw a stone into the opening B so that it hits the receptor C.

 

It is evident that the velocity of the stone must be a function of the rotating rate of the shell A and of its radius. If I throw a stone too slowly, the stone will not hit the receptor. If I throw too quickly again the stone will not hit the receptor.

 

IOW the rotation rate of my device will give the only specified velocity that the device will understand as "stone" by ringing the bell.

If 100 people all around throw stones in my device at random velocities, only the stones that travel at the specified velocity will be able to ring the bell.

 

So I made a device that understands only and only one velocity.

 

I guess there must be other ways to obtain a similar result.

For example one can replace the B orifice with a 2nd receptor and make the bell ring only when both receptors understand the stone. In this case the shell can vanish.

Edited January 11, 2013 by michel123456

[swansont]

Similar devices are used for velocity selection of atomic beams. Chopper wheels, each with a slot in them and placed some distance apart, allows you to select a velocity range. (or one wheel and some pulsed generation scheme). The concept has also been applied to speed of light measurements.

[michel123456]

Now, going one step further, we know that velocity is relative: what my device measures is the same with what measures an observer upon the stone.

IOW if the observer on the stone has to measure the velocity of my device, he will measure always the same velocity.