# Thread: (Layman Science Series) Week 6 - How does breeze make you cool when you sweat?

1. ## (Layman Science Series) Week 6 - How does breeze make you cool when you sweat?

Intro
I am trying to post a science/physics question of varying difficulty each week for this year, and maybe a monthly question of greater complexity.

The Rules are:
Answers must be complete, and each statement must be sound/logical.

More than one answer can exists, until its proven false. Hypothesis and theory varies, but scientific logic used must be sound. For example, no marks for cyclic logic. Another example, in cause and effect, no marks for declaring a cause without completely deriving that cause from a generally known and proven fact.

The better the answer, then the more points awarded. Answers can always be updated at anytime as we learn something new everyday.
(I do not claim to have THE answer. I will just attempt to provide a possible answer)

The greater the difficulty, the greater the points. I will give an answer at end of week/month ... hopefully. Repeating my answer awards no points, you will have to come with a better or alternate answer.

I emphasize that Logics is key to getting points aka "Sound logics" aka "there is no other type of logics". It is either logical or illogical. (Some people claim other forms of logic like administrative logistics which they essentially hide some of the steps because such steps are nefarious and then claim that they are using a special type of logics. That will give you zero marks here. Each step must be given) I believe that we are smart people here, so we logically know that "Many people having the same answer" does not automatic conclude, or imply, that that answer is THE answer. What can make an answer THE answer is sound logics and proven experimental tests.)

Question
How does breeze make you cool when you sweat? [4 marks]

Difficulty
A-Level Physics

Site share of the week/month

2. Explanation 1
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Temperature is average energy, mostly k.e. (kinetic energy) of molecules
Some molecules are in higher energy levels than some (faster)
Energy of one molecule is distributed (via entropy) in the degrees of freedom (from energy levels of electrons, rotational energy of the molecule, translational energy, oscillation/spring energy in bonds)

When breeze (air molecules) hits the liquid, the air is forces to flow tangential to the liquid surface
The source air also has molecules that are in various energy levels, however much of the energy is in bulk translational energy in the same direction (somewhat ordered)

At the boundary of the liquid and air, molecules from both interact

Some molecules of the the liquid gain enough translational k.e. to be ripped from the liquid. This would be mostly the molecules that had a higher energy level.

There is also a higher probability of evaporation than condensation due to the higher concentration of water molecules in sweat that in the breeze.

This loss of higher energy molecules to evaporation lowers the average energy

The rest of the bulk translational energy is passed to ordered low frequency sound that travels out of the liquid and air, and not absorbed as heat

Also, the fewer molecules in the boundary that gain k.e. (not resonating with the bulk sound) and do not escape to vapor eventually disperse that ke to the other degrees of freedom, and thus eventually have less ke and contribute slightly to heating, while the cooling effect described before dominate.

Also, the water molecules that go into the air are less volatile than normal steam molecule, and as its ke energy dispersed in its molecule's degrees of freedom it makes it cooler for an air mixture molecule. Humidity increases slightly.

Explanation 2
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Nicola Tesla had believed that everything was based on vibrations

Imagine the breeze was a big sine wave (like sound). Almost no interaction would occur with the sweat to cause heating or cooling as the low frequency sound wave would just pass through. To achieve this the wind would start soft, move just the first layer (of molecules in the sweat) together, and so increase as the load increase (molecule increasing squeeze onto its neighbor in cumulating layers), without disturbing the overall orientation of the molecules in the sweat. Just picture a big sound wave passing through from air to liquid

Now consider normal breeze (it is far from a sin wave), this would be a broadband spectrum of frequencies in comparison (many frequencies of energy). The sweat surface has molecules of different energy frequencies, and can receive at their level of energy frequency

When the breeze and sweat interact. Some of the breeze frequency is absorbed by the sweat via matching some of the input frequencies (energy level) and load. The majority is reflected back as turbulence, and some still passes through as sound. The molecules that received energy via load balance will evaporate, thus still reducing the average energy of the sweat

Imagine this question: why does waves push away sand but not a very big rock

When a big tidal wave hit a megalithic rock, it would take immense energy for the rock to move like the wave, many atomic bonds would have to be broken simultaneously
Instead what happens is the rock produce a reactive force of much higher frequency (molecular bonds = strong potential & short distance) that energy "incoming" is "resonated out" at a higher frequency which then causes turbulence in the wave and the waves energy is not transferred to movement of the rock.
(Tesla said that we can view everything as frequencies and vibrations)

3. Imagine this question: why does waves push away sand but not a very big rock
Deeper explanation in thinking in terms of frequencies

Don't just think about the frequency of the sea wave.

There is the frequency in energy of every atom. More specifically, there is frequency in every energy packet and in every energy in each degree of freedom.

This energy, when it interacts with other energies, has a finite time when it transitions from it kinetic form to potential form.

Generally, from kinetics to potential, there is an oscillator (p.s. V and I is also a form of potential and kinetic) . There is a certain time characteristics of different systems, an intrinsic property.

When two balls of equal mass collide, b1 and b2, say b1 in moving and b2 is at rest, there is a transfer of energy. Just before the collision, picture the moving ball b1 in slow motion approaching the rest ball b2.

During the energy transfer, b1 decelerates to rest and b2 accelerates to a final value v equal to the initial velocity of b1. Bear in mind that even though this occurs quickly, it does take a non zero time (and is characteristic of the rate of kinetic to potential for that system) This is actually a idealizations of real world collision with very elastic balls. In a perfect elastic ball collision, none of the energy of the collision goes to sound or heat, etc, which is the case when you go down to the basic atomic, as there is less ways in which that energy can be dispersed between two simple systems.

As soon as b1 interact with b2, potential increases, the rest ball b2 starts to accelerate and the moving ball b1 starts to decelerate. I suspect a sinusoidal variance. b1 experience cosine deceleration in ke energy to 0, and a sine increase in potential. b2 will already start to acceleration as soon as the potential is non 0, an b2 reaches final velocity and full energy of b1. This takes a finite time of the system. I suspect also that the more perfect the sinusoids the more efficient the energy transfer at a macro scale, but will be perfect at the micro scale. Energy flows by the same amount, what b1 looses, b2 gains

Here the is conservation of energy and momentum: Perfectly elastic. Also, there was perfect load balancing from source to destination as the moving ball comes to perfect rest. No movement was reflected or lag behind ie if ball 1 had some +/- velocity after the collision. And that energy would not fully transfer either from b1 to b2. It B1 was smaller in mass (or larger) then there would be load unbalancing. The smaller ball would slow down more quickly than before giving it a higher frequency and the larger ball would accelerate slower giving it a lower frequency. Energy get dispersed to different frequency forms

Now there are oscillations, if energy goes from potential to kinetic form but it's frequency remain the same in that system. And for this purpose I would use that the energy packet has not really changed form.

Now for a big sea wave. There is not just the frequency of that wave, but every particle in it has its own energy, even further, each degree of freedom

When the wave interacts with the megalithic rock, the first layer of the wave interacts with the first layer of the megalithic rock. Potential build up, but the layer of the megalithic rock is strongly bonded with the 2nd layer of the rock and barely accelerates. Next the reactive force of the rock pushes back at high frequency, and cause turbulence disruption of each consequent layers of the sea wave. The wave would have to be really big to slowly accelerate the rock (or the incoming wave would have to also be a large rock.)

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