- #1
aceofspades
- 10
- 0
Heres something interesting I noticed the other day.
I had just made a cup of coffee in a ceramic mug,
and had just finished stirring it. Absent mindedly,
I started picking up my spoon and dropping it into
the cup at roughly half second intervals.
On doing this, I noticed something very peculiar
that baffled me at first. Each time the spoon hit
the bottom of the mug, it rang with a frequency
that was noticably higher than the time just before.
I kept this up for a while, experimenting by
dropping the spoon from different heights, I tried
increasing and decresing the time intervals between
spoon drops, but none of these things changed the fact
that the frequency increased steadily each time the spoon
dropped.
After a while, I noticed that the coffee in the mug was
still swirling, but very slowly. I stirred it rigorously,
and this time the frequency was low and once again increased
steadily as the swirling slowed.
Does anyone have any ideas as to why this happens?
Here was my initial thought:
The swirling coffee exerts a centrifugal force on the
walls of the mug, as the swirling slows due to friction,
this force decreases. Could it be that this centrifugal force
exerts enough strain of the walls of the mug to alter the
pitch of the sound produced to the extent, that the change in
frequency can be clearly heard after just half a seconds change
to the centrifugal force.
The reason I am asking is that as I am sure you can imagine, this
force must be miniscule, and even when the coffee was hardly
swirling at all, the change in frequency was still easilly
discernable.
Im curious to hear any other possible explanations you people
might be able to think up.
I had just made a cup of coffee in a ceramic mug,
and had just finished stirring it. Absent mindedly,
I started picking up my spoon and dropping it into
the cup at roughly half second intervals.
On doing this, I noticed something very peculiar
that baffled me at first. Each time the spoon hit
the bottom of the mug, it rang with a frequency
that was noticably higher than the time just before.
I kept this up for a while, experimenting by
dropping the spoon from different heights, I tried
increasing and decresing the time intervals between
spoon drops, but none of these things changed the fact
that the frequency increased steadily each time the spoon
dropped.
After a while, I noticed that the coffee in the mug was
still swirling, but very slowly. I stirred it rigorously,
and this time the frequency was low and once again increased
steadily as the swirling slowed.
Does anyone have any ideas as to why this happens?
Here was my initial thought:
The swirling coffee exerts a centrifugal force on the
walls of the mug, as the swirling slows due to friction,
this force decreases. Could it be that this centrifugal force
exerts enough strain of the walls of the mug to alter the
pitch of the sound produced to the extent, that the change in
frequency can be clearly heard after just half a seconds change
to the centrifugal force.
The reason I am asking is that as I am sure you can imagine, this
force must be miniscule, and even when the coffee was hardly
swirling at all, the change in frequency was still easilly
discernable.
Im curious to hear any other possible explanations you people
might be able to think up.
Last edited: