# Proof of Momentum??

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Read a book about physics - Foundation AS3 Animation Making Things Move

and there is the equation i can not prove.

why
(m0 * v0) + (m1 * v1) = (m0 * v0F) + (m1 * v1F)
(m0 * v0^2) + (m1 * v1^2) = (m0 * v0F^2) + (m1 * v1F^2)

can get

v0F=((m0-m1)*v0+2*m1*v1)/(m0+m1)
v1F=((m1-m0)*v0+2*m0*v0)/(m0+m1)

[attachment=31182:momentum_prove.png]

Edited by tracegame

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why prove it?

either they are right, and it works, or they aren't and it doesn't. if it doesn't, go get a real physics book.

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I think these are the steps I would take:
(1) Pick coordinates in which v1 = 0
(2) Use the equation of conservation of momentum to get an expression of v1F as a function of v0 and v0F.
(3) Substitute that expression in the equation for conservation of energy.
(4) Solve the corresponding second-degree equation (one root will be 0, which corresponds to no collision, so we are interested in the other one).
(5) Undo the change of coordinates from step (1).
(6) Now that we have an explicit formula for v1F in terms of m0, m1, v0 and v1, we can swap the 0s and the 1s to get a formula for v0F.

Let us know if you get stuck anywhere.

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Find a friend to help work this out,i'm really not good at Algebra.

Why prove it,because usually i just copy,paste codes without thinking,

now i'm trying to do things step by step,and try to figure out why these code work,

no more blackbox coding.

[attachment=31191:Momentum.png]

Edited by tracegame

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Why prove it,because usually i just copy,paste codes without thinking,
now i'm trying to do things step by step,and try to figure out why these code work,
no more blackbox coding.

good for you!

i'd recommend a few books:

physics by tippler - it will tell you everything you will ever need to know about physics.

a good calculus book with analytic geometry - Swokowski does a good job. some stuff is useful.

a good book on linear algebra for 3D stuff

and a good book on engineering mechanics: statics and dynamics. helps with application of more advanced physics.

discrete math and probability and statistics can also be useful.

you can always go to the bookstore at the local university to see what books they are using these days for these subjects.

only downside is that textbooks aren't cheap, and some books target the novice, and some don't. many assume a certain amount of background knowledge.  following the usual progression of subjects (geometry, algebra 1, algebra 2, trig, functions, analytic geometry, calculus 1, calculus 2,calculus 3,, etc) guarantees having this background knowledge.

when pursuing individual study without having all the background knowledge first, you'll often have to backtrack and learn some related subject first before you can continue with the subject at hand. eventually you'll find all the info you need in books or online, and learn it all.  then you'll be ready to code with full knowledge of what your doing, and how to make it do exactly what you want.

everything you need to know is out there. all you have to do is go find it.

i wish you good luck in your pursuits.

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