Math Equations.

[Longstreet]

Does anyone know of any math equations - particularly used in the military - that people use to help make decisions? I teach Grade 7 math and found that my students really struggled with equations and variables partially because they did not fully understand their significance in the real world. I used the classic E=MC2 as well as the equation the police use to determine the speed of a car using its skid marks, but only a few of my students got it. I would like to put together a list over the summer so that they will be better able to see the power of equations and hopefully see their importance. Please note that if you can provide one, can you please identify the variables and no you do not need to explain it with an actual example. I just need to know the equation and what it does. Thanks.

[1stindoor]

I learned this one over 20 years ago in the Water Infiltration Course in Key West, we called it the D street formula:

D=S x T

Distance = Speed x Time. Using Algebra...therefore:
Speed = Distance / Time
Time = Distance /Speed

This was used when doing estimations for mission planning with our boats.

[Richard]

Jayson,

The D=KAV formula we use for computing static-line parachute drift in the military might be a good one for your students to play around with.

D = Wind induced drift in meters.
K = Wind drift constant for type of parachute.
A = Drop altitude expressed in hundreds of feet (500 feet would be expressed as 5).
V = Velocity of wind in knots (either MEW or surface wind measurement).

An explanation of the formula and examples of its use can be found in TC 3-21 Static Line Parachute Techniques and Training Chapter 21 Section 2 (21-2 p436 at the pdf link below).

http://www.benning.army.mil/infantry...CT%202013).pdf

Gutes lesen.

Richard

[Longstreet]

D=S x T

Distance = Speed x Time. Using Algebra...therefore:
Speed = Distance / Time
Time = Distance /Speed

Thanks 1stindoor. I forgot about that one as well as Pythagorean's theorem. Thank you too Richard. Next year I will be teaching math and science to an all boys Grade 8 class. As mentioned I hope to put together a list of equations to show my students how math is used in everyday life. The fact that I can use military equations will help keep interest levels.

Question: The true math teacher came out of me the other day when watching Black Hawk Down. When SHTF and everyone is coming in to reload - in particular the Little Birds - I started thinking how did command know how much ammo to keep on hand? Then I started to think about fuel supplies as well as food stores. Is there a math equation that is used to determine each of these? Anyone?

[CSB]

The amount of TNT needed to destroy a timber beam (applied externally) is:


P= D ^2 / 40

(That's P equals D squared, divided by 40)

Where:
P = Amount of TNT in pounds
D = Dimension of beam in inches

If the engineer can auger a big enough hole to the center of the timber,
the amount of TNT for an internal charge drops to:


P = D ^2 / 250

Notice how the constant divisor increased in size, decreasing the amount of TNT needed.

====================

For a bulk steel cutting charge, simply estimate the number of square inches
in the steel beam, then use:

P = 3/8 A

Where "P" = Pounds of TNT and "A" equals the Area of the structure in square inches.

For steel bars, cables and chains, simply use P =A. Sounds simple, but a 2 inch in diameter steel rod has a cross section of?

... Anyone? anyone?

Pi x R ^2 (The area of a circle) produces the area.

for a one inch radius (2 inch diameter) that's 1 x 1 x 3.14 = 3.14 inches cross section, yielding 3 1/4 lbs of TNT.

[Golf1echo]

Your intent reminds me of a story about knots, specifically the Bowline. The way it tends to be taught is about a rabbit coming out of it's hole and going around a tree and back down it's hole... but only half the class got that. When questioned the other half of the class was from the city...once the emphasis was changed to a homeless person getting up out of the dumpster, going to pee at the telephone pole and getting more wine and then back into the dumpster, everyone was happily tying the Bowline.
Being able to relate to the premises is a big part of the battle...Maybe something on cell phone conductivity and range?

[spottedmedic111]

Learned these in first year community college so they might be too advanced...or not. This first set of equations shows how to calculate investment growth.


Compound interest equation

P = C (1 + r/n)nt

Simplified compound interest

P = C (1+r)t

P = future value
C = initial deposit
r = interest rate expressed as a fraction, e.g. 0.04
n = # of times per year interest is compounded
t = number of years invested


This equation is more complicated but is used to calculate loans, such as mortgages.

B = A (1 + r/n)nt - P (1 + r/n)nt - 1 / (1 + r/n) - 1

B = balance after t years
A = amount borrowed
n = number of payments per year
P = amount paid per payment
r = annual percentage rate (APR)
t = number of years

[BMT (RIP)]

Reminds me of my 5th Grade teacher.
She started ever new step in math on how we would use it in our everyday life.
All the girls wanted to be teachers or nurses and the boys policemen or fireman.

Sixty six years later we still talk about Miss. King!!

BMT

[Longstreet]

The examples given have been excellent. Thank you all. And please they do not need to be military based. Any equation that would spark an interest or allow my students to make a connection will do just fine.

Please keep them coming!

[Pete]

Jeez - Please don't bring up imaginary numbers.

[1stindoor]

I used to have a physics teacher in high school who used to use everyday examples to prove his point/thesis in his classes. Some of his better examples...and I can't remember the specific equations:

You're at the mall and see a tall beautiful woman wearing 3" heels with a 1/4" diameter base on the heel. Assuming she weighs 125 lbs, and her weight is distributed 75/25% (75 being front of foot and 25% at the heel). How many foot pounds of pressure downward is she exerting at the heel?

While filming Mutual of Omaha's Wild Kingdom, Jim assists the local tribesmen secure a lion to a pole to be carried between two of their warriors. Assuming the lion weighs (whatever a good lion weighs, I reckon) the pole is 10 feet long, and the height difference between the two carriers is 12"...where would the lion best be placed to evenly distribute the load between the two tribesmen?

[Longstreet]

I used to have a physics teacher in high school who used to use everyday examples to prove his point/thesis in his classes.

My physics teacher used to do the same thing. The example I remember best was when he used some equations to prove a scene from James Bond to be impossible - yeah I know it is James Bond, but it was still cool to see the math. We looked at the film The Man With The Golden Gun and the scene where James jumps his car over a river with the vacationing sheriff. Using the time & trajectory of the car, he was able to prove that the spiralling car was impossible as there was not enough space.

Unfortuntaely I sucked at physics and advanced math. So I am now cursed to forever teach math from Grades K-8, heh-heh.

[RATT31C]

Jayson, here is what my math instructor told me, "you have to learn the lingo". He put a big emphasis on learning the vocabulary. Good instructor, I chose him for all three of my math classes. Here are a couple that I used all of the time as a radio guy and as a IEW/ISR Technician, also some that I learned in his classes. I have a lot more if you would like me to PM or e-mail them to you.

Ohms Law
I=V/R, I= AMPS, V =VOLTS, note E can be seen instead V and R = resistance, R in this relation is constant, independent of the current.

Antenna Length
1/4 wave = 234/freq in MHz
1/2 wave = 468/freq in MHz
1/1 wave = 936/freq in MHz

Wavelength of a musical note
fw=343
f= frequency, w=wave
ex 343/240waves=1.429

Hero's Law, this works on all triangles except right triangles. This one is different than Pythagorean theorem but still kind of fun because I get to push buttons on a calculator and get bananas.

Finding the pitch of a roof
rise/run
ex 6' rise/24' run (note set to 12") 6 over 24 = x over 12"

For the gearheads (car guys) the compression ratio
expanded volume/compressed volume (set to 1)

Gear Ratio
Driven Gear/Drive gear

[Sdiver]

Originally Posted by Longstreet

Jayson here and my physics teacher used to do the same thing. The example I remember best was when he used some equations to prove a scene from James Bond to be impossible - yeah I know it is James Bond, but it was still cool to see the math. We looked at the film The Man With The Golden Gun and the scene where James jumps his car over a river with the vacationing sheriff. Using the time & trajectory of the car, he was able to prove that the spiralling car was impossible as there was not enough space.

I'm not following how he said it couldn't be done?
That gag was indeed genuine. No wires or mirrors were used.
What you see on film is how it actually happened.

The cork-screw car jump was apparently conceived years before the movie went into production. Researchers at Cornell University were studying rollover collisions for the National Highway Traffic Safety Administration and they did a computer simulation of the barrel roll stunt used in the film. Race car driver Jay Milligan, who is the promoter of the American Thrill Show during the 1960s and 1970s with the sponsorship of the American Motors Corporation, did actually perform the barrel roll stunt, known as the Astro Spiral Jump and it debuted on January 12, 1972 at the Houston Astrodome using an AMC Javelin. Milligan was contacted by Albert R. Broccoli during an American Thrill Show performance in Hershey, Pennsylvania where he wanted the stunt performed in a James Bond film. The producers Harry Saltzman and Albert R. Broccoli allegedly took out patents and copyrights on the stunt as they did not wish it to appear in another movie before they had used it. The 360-degree car-spiraling jump over a canal was performed in just one take by uncredited British stuntman 'Bumps' Williard as 8 cameras simultaneously captured the spectacle. So potentially hazardous was nature of the stunt, divers, ambulances and cranes were on standby alert in case of any catastrophic consequences. The stunt was so rapid that the film is shown in slow motion. Williard was given a large bonus for completing the jump on the first take. Jay Milligan did actually perform the driving stunts with the AMC Hornet used in the film - AMC provided 15 vehicles used in the film (some of them where AMC Matador police cars). There were two AMC Hornets used for the spiral jump stunt and one of them is still owned by Jay Milligan - which is the backup vehicle while the other one is in a museum. The jump is also credited with being the first stunt ever to be calculated by computer modeling.

http://www.imdb.com/title/tt0071807/trivia

[PSM]

Originally Posted by Sdiver

I'm not following how he said it couldn't be done?
That gag was indeed genuine. No wires or mirrors were used.
What you see on film is how it actually happened.

This makes you wonder, though. The movie landing looks a little suspicious.

Movie: https://www.youtube.com/watch?v=hh0VF6s-UYU

Top Gear: https://www.youtube.com/watch?v=iVRmFQixqsc

Pat