Examples of Applied Physics

[hmbld]

Well, I am not up to proving anything, just wanted to have a conversation. Apparently  a lot of what is taught  in grade school has not been proven, and you have no answers for how things I observe on earth really work. You just dispute commonly accepted information with no new information. 

[hmbld]

5 minutes ago, Enoch2021 said:

I don't think that's the Case; the 2 questions are not that complicated.

 

Again Irrelevant (Red Herring Fallacy) to the subject.

 

regards 

So pretend it's a new subject. Why do my ears pop when I climb a small hill?

[AngelKaring]

Im a super whiz in the kitchen and sewing room but I do enjoy watching you guys enjoy it, brainstorm on!!

[other one]

2 minutes ago, hmbld said:

So pretend it's a new subject. Why do my ears pop when I climb a small hill?

air pressure behind your ear drum changes with the air pressure you exert with your lungs breathing a bit harder.

[Enoch2021]

2 minutes ago, hmbld said:

Well, I am not up to proving anything, just wanted to have a conversation.

Well those two things aren't Necessarily Mutually Exclusive.

 

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Apparently a lot of what is taught in grade school has not been proven

Oh it goes much much further than Grade School.

 

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you have no answers for how things I observe on earth really work.

That depends on the "Things" you observe.

 

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You just dispute commonly accepted information with no new information. 

Well 'commonly accepted' doesn't offer any Veracity to what's being "Accepted".

 

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So pretend it's a new subject.

Why?? Just answer the questions. (You or Anyone... especially the "Physicist" 'GandalfTheWise')

I stopped "Pretending" many years ago.

 

regards

[hmbld]

9 minutes ago, other one said:

air pressure behind your ear drum changes with the air pressure you exert with your lungs breathing a bit harder.

Hmmm. I can work at the same altitude and breathe harder, yet my ears don't pop. Only when I go down a hill or up a hill. Or, when I drive my lungs work the same when driving up a hill or down a hill, yet my ears only pop when not driving a flat road. 

[hmbld]

16 minutes ago, AngelKaring said:

Im a super whiz in the kitchen and sewing room but I do enjoy watching you guys enjoy it, brainstorm on!!

Sounds like your more accomplished than we are with this thread!  It's all for fun. 

[GandalfTheWise]

9 minutes ago, Yowm said:

Why would (1ft/12in) times anything change a calculation as any number times one remains the same?

Good question as it touches upon the meaning and importance of units in mathematical descriptions.  1 foot is not the same as 1 inch is not the same as 1 pound.  It is not the 1 that matters so much as the unit that matters.  Writing it as (1 ft/12 in) or (ft/12 in) would be equivalent.  It is an issue of keeping units well documented and consistent on both sides of an equation.

In this case it clearly shows the reader that (1ft/12in) is simply a conversion factor whereas only dividing by 12in can cause confusion as to whether or not it is a fundamental distance that is part of the equation.

[GandalfTheWise]

I was rather curious to see how atmospheric pressure changes with altitude and how that compared to actual weather data.

I use Mathematica for much of my professional work.  See wolfram.com for more details on it.  It is a powerful mathematical package with a lot of curated data and information built into it.  I used their built in standard atmosphere functions, weather data, and city information to generate an interesting graph showing how the earth's atmospheric pressure changes with altitude.

The blue line shows the 1976 version of the US Standard Atmosphere Model.  This model gives what is essentially the average value of temperature, density, pressure, and other quantities at various altitudes in the atmosphere.  It is used for aircraft engine design, ballistics, and other applications where various properties of the atmosphere are important to know at different altitudes.   This model assumes that the atmosphere is dry and there is no wind or other such effects.  Users of the model must add the effects of wind, water vapor, precipitation, and other such things themselves.

Various sites on the web have more information about this model.  The wiki page isn't too bad of a place to start. https://en.wikipedia.org/wiki/U.S._Standard_Atmosphere

The red line shows the estimated effect of water vapor in the atmosphere.  This is a very complicated type of interaction that has different aspects of things to consider.  The main thing to know is that it will reduce the atmospheric pressure by a few percent or more depending on temperature, dew point, and other things.  The red line is set to a 5% reduction to provide a reference point for the city information.

The 4 cities give the average raw atmospheric pressure measurements over a 2 year period from 9/10/2015 to 9/10/2017.  I pulled this in from the Mathematica weather data set.  As can be seen, they all sit a few percent below the dry atmosphere pressure curve as would be expected.

[Justin Adams]

16 hours ago, other one said:

actually it is very easy to fly a plane (unless you are a stunt or fighter pilot)......   it's the landing part that's tricky.   First you gotta find where you want to land and finish up with the pointy end up.

OK. Well it is 1974 and we are going on a trip from Edmonton to Yellowknife. You fly - I'll watch.
I'll let you do the flight planning as well. Here are some reminders. 
Since it is Sparsely Populated Area, we will need the emergency gear. We will stop on the way to refuel. The Arrow burns about 8-10 GPH (check if that is Imperial or USG). Make a note of the following frequencies in the log:
GRND here, TWR here, and at destination. Transponder freq(s). Departure and Term. Area freq, plus the military base tower we will pass just to the north. We'll give them a courtesy call on the way by. 
Be sure to list on our preflight a check using the local VOT and local NDB. VOR is needed to get a fairly good initial heading, but the NDB will be our main X-Ref Nav-Aid until we get closer to the destination. Since our plane only had one NDB, we need all the freq. listed for easy ref. So make a note also of en-route radio stations we can fix on. Check the ELT. 
It will be a normal VFR dead reckoning flight so the winds aloft are important along with the weather. We can check the automated weather reports on the way.  Because it is minus 30F right now, the lapse rate means it will be colder up there. Verify the Dew Point Spread along the route. Decide on a legal altitude and compute ETA, ETE, CH, (for both legs) and estimated Ground track (don't forget the deviation) and fuel needed per leg. Mark the course on the sectional chart. As we go we can check actual GS and track and make any necessary adjustments. You can go and do the pre-flight and check for any PIREPS, NOTAMS etc. TimeAir does the trip a lot so they will update the winds if they are different than the forecast. 
We will probably encounter White-Out conditions nearer the destination, but since it will be getting dark by then, a few lights on the ground will give us a better visual reference. Don't forget the cockpit  flashlight! We will have Yellowknife Radar give us a DF steer when we get closer - they like the practice. We dont have DME capability, so  Radar is normally glad to help and give us a precise location and track.
Do not forget to CLOSE the flight plan when we arrive. Wear your woolens. Off you go and do the weight and balance when you have got the fuel calculated. Remember we have the extra weight of the mandated emergency gear in back. You do the walk-around and don't freeze!
One last thing before we fly during run-up. Double-check the ELT is not broadcasting - we don't want SAR after  us before we even take off! 
The way the pilots here bounce these planes around, sometimes they set off the ELT.