Formulae

[Somar]

I made this thread for all of the mathematically impared, in hopes that people would post useful formulae *points at Mathonwy and Rydeman*. They can be about any thing, physics, optics, biology, and math anything you think is useful. Please post! You'll get to show off your knowledge as well ;] (Note: If you want I'll list all the derivitives and indefinite integrals, but I don't think you'd want them hehe)

I'll start:

Physics:
Trajectory:

x = x0 + v0*cos(@)*t;
y = y0 + v0*sin(@)*t - .5*-g*t*t

Where v0 is the initial velocity, x0 is the initial x co-ordinate, y0 is the initial y co-ordinate, g is the gravity (Earth's is 9.8), and @ is the initial angle of the projectile. You have to loop it over and over, adding to t, since t is time.

Time it takes to fall:

t = sqrt(h/(g/2))

Where t is the time it takes, h is the height in meters, and g is the gravity. I just threw this one in cause I think it's neat ^_^

Hunt the Wumpus!
Somar
[Edited by Somar on 08-16-2001 at 06:12 PM]

[McChicken Nuggets]

hi

here are some of my favourite trig relationships, ive just copied them from one of my other posts. i always find these useful

cosA*cosA + sinA*sinA = 1
secA*secA = 1 + tanA*tanA
cosecA*cosecA = 1 + cotA*cotA
cosA*cosA = 0.5(1+cos2A)
sinA*sinA = 0.5(1-sin2A)
cos2A = cosA*cosA-sinA*sinA
sin2A = 2sinAcosA
tan2A = (2tanA)/(1-tanA*tanA)


a cosb + b sinb = R cos (b-a) where R = Ö(a*a + b*b) and cosa = a/R sina = b/R

ill post some of my favourite projectile ones latter, and perhaps some other pretty equations, but here are a few for you equation junkies out there. dont lie, i know your out there.

thanks
Matthew