View Full Version : The JetBlast mathematical formula thread

Onan the Clumsy
25th Mar 2005, 15:22
Remember all those formula you learned at school, but never really used?

Well how many can you remember?

I'll start with an easy one...

"Half base times perpendicular height"

25th Mar 2005, 15:28
Pythagorean Relationship. The square on the hypotenuse is equal to the sum of the squares on the other two sides.

25th Mar 2005, 15:29
Used both of those many times. Haven't used e=mc squared very often, though.

25th Mar 2005, 15:35

expenses exceed income for pilots.

Given an even chance between the right and wrong choice, I will always get it wrong...

I am always wrong: she is always right.

I'll stop there.

25th Mar 2005, 16:03
They taught us *how* to differentiate and integrate, but they never taught us *why*.

I can still calculate the square root of anything longhand, though, even 40+ years on.

25th Mar 2005, 16:08
Rule of 72's for interest calculation.


25th Mar 2005, 16:24
1 mole= 6.02214 x 1023 particles

2 moles = party time :E

25th Mar 2005, 16:30

25th Mar 2005, 16:32
If anyone can tell me how to insert a square root symbol I've got a formula

25th Mar 2005, 16:34
I hear them moles like a square root :E

25th Mar 2005, 16:36
Benn done many a time but...

Relationships = money x time

the saying "Time is money" holds true, so:

Relationships = money^2

the saying: Money is the root of all evil holds true, so:

Relationships = root evil x root evil


Relationships = evil

25th Mar 2005, 17:09
f00l + m0ney = 5oon parted.

25th Mar 2005, 17:55
Dammit, I wanted to say the Schrodinger equation!

25th Mar 2005, 18:04
cat + box = can't see pussy.

25th Mar 2005, 18:08
If anyone can tell me how to insert a square root symbol.........
V-e-e-e-e-e-e-e-e-e-e-e-e-e-e-ry carefully, lots of lubricant.

Them sharp corners are murder. :uhoh:

25th Mar 2005, 18:55
A rather un-PC one:

"The angle of dangle is directly proportional to the throb of the knob provided the urge stays constant"


25th Mar 2005, 19:02
RTFQ = 1/2 TFA

Read the F***ing Question = Half The F***ing Answer

25th Mar 2005, 22:57
I dunno if this has been done before, but it's one most of us here are thankful for, if not aware of

C.1/2pV^2.S or C.q.S

The Lift Coeffecient.

Never has a peice of Maths ever been more exciting (not a hard feat, I know....)

25th Mar 2005, 23:29
This thread is drifting towards physics.The Lift Coeffecient.
is actually a very specific consequence of Navier-Stokes equations (http://scienceworld.wolfram.com/physics/Navier-StokesEquations.html)
:8 :8

26th Mar 2005, 00:15
(All work + no play)* Johnny = dull boy.

26th Mar 2005, 01:52
The squaw on the hippopotamus is equal to the buns of the squaws on the other two hides.

Or something like that, anyway...

Genghis the Engineer
26th Mar 2005, 01:55
Grainger, I'm embarrassed to say I can't remember what that equation is - is it something to do with vortex flow?

It's a bit lacking in originality quote other people's equations, so here's one of my own. It models the deceleration rate of an aeroplane after an engine failure, if the pilot tries to maintain height.

dV(ind)/dt = (9.54 x Tau_sub_d x SQRT_sigma / G) * ((Vs/Ve) + (Ve/Vs))

Where Ve is the best range glide speed (L : D.max speed), G is L / D.max value (or best glide ratio, which is identical), and Tau_sub_d is a factor based upon the aircraft's characteristics, primarily wing loading.


B Fraser
26th Mar 2005, 07:23
if 5x + 6y = z

go and do something more interesting instead :p

26th Mar 2005, 08:27
1+1=2 2+2= ?

Anyone with the answer?


26th Mar 2005, 09:18
Eddie Izzard.....................

The drag coefficient??


26th Mar 2005, 13:05
If Tom has X apples and Mary has Y apples how many oranges has Fred got?

26th Mar 2005, 13:09
For very small angles, the value of the angle in radians and its sine are almost identical.

26th Mar 2005, 13:17
Fred hasn't got any oranges...................thems genetically modified qumquats!

26th Mar 2005, 15:13
" s=ut+1/2 at squared". Anyone remember what that referred to? 53 years have passed since I did!

26th Mar 2005, 15:39
Constant acceleration equation, sailor.

s is the distance travelled in time t whan you start at an initial speed u and have a constant acceleration of a in the same direction (if they're not in the same direction you have to get into vectors and components, and - trust me - you don't want to get into vectors and components unless you have to...) If you think about it, it's just a complicated way of doing average speed.

Genghis: it's the time-independent version of the Schrodinger Equation. You can use it to find the energy levels of the Hydrogen atom, that sort of thing.

G :8

26th Mar 2005, 16:31
If Jack and Jill go up the hill both with $2.50 each and Jill comes down with $5.00................ :E :E

26th Mar 2005, 20:41

In this case Vw is the Swell Propogation Velocity component and g and Hb being Acceleration due to gravity and the height of the swell at breakpoint. C is of course a dimensionless numerical constant, with a value of 1.25.

Or as any surfer will tell you how to measure a break (or part of the answer)... now you wondered what they were all doing in the back of their VW's.....

27th Mar 2005, 14:52
Big 3 from mechanics lessons:

S = UT + 1/2 AT^2

V^2 = U^2 + 2AS

V = U+AT

27th Mar 2005, 19:31
When I was in school we referred to the Schrodinger Equation as the Shorten-your Equation.