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# Need help catching up on my physics.

[FuN]goku
So, I just missed about a week and a half of school due to H1N1 , and my Physics teacher isn't the best at explaining things to begin with...

That being said, I missed pretty much everything on forces, how to draw free-body diagrams, what each of the forces are etc. He tried to explain it to me when I asked him, but it wasn't the best of explanations.

Also, when I came back, they had started doing stuff on momentum 2 days beforehand. I kind of understand this stuff, but I'm slightly confused on a few things. The problems we've been doing are like m1v1 + m2v2 = ......
Something like that, I don't have any of my papers in front of me right now so, I'm not really sure what the rest of the equation is offhand.

But yeah , I missed a couple assignments which he wants in by Monday.

So if someone can explain forces and momentum to me , or even give me some sort of resources, that would be greatly appreciated, seeing as my teacher's explanations aren't the best.
Bikerman
 Quote: The problems we've been doing are like m1v1 + m2v2 = ......

That is basic conservation of momentum.
If you want to measure the momentum of something then you multiply the mass by the velocity.
(I take it you understand the difference between velocity and speed?)
Momentum is a 'conserved' quantity - that means that the total momentum after an event (such as a collision) is the same as the momentum before the event.
The following is probably worth a read - then you can come back with any specific questions.
http://www.lightandmatter.com/html_books/2cl/ch04/ch04.html#Section4.1
Dennise
A force is what causes any body change its motion. Newton gave us the wonderful equation F=ma. This says that if you want to change a bodies motion (i.e. acceleration) you must apply a force that depends on both the mass of the body together with the degree of motion that you wish to change.

Momentum can be linear or angular and is a measure of the energy contained in a moving body and thus how much force is needed to change the momentum. Linear momentum is defined as p = mv. Just as energy must be conserved in a closed system, so must momentum be conserved in a closed system. This conservation can be used to find unknowns in many physics problems.

Hope this helps.
Bikerman
A very good web-resource for brushing-up basic physics is the hyper-physics site.

http://hyperphysics.phy-astr.gsu.edu/Hbase/hframe.html
Afaceinthematrix
 Bikerman wrote: A very good web-resource for brushing-up basic physics is the hyper-physics site. http://hyperphysics.phy-astr.gsu.edu/Hbase/hframe.html

That isn't too bad of a link to brush up on basic physics. I recently found, however, that one of the best sources for any physics needs are the incredible Feynman Lectures of Physics. However you must already have a slight understanding of mathematics and science to fully comprehend what he is saying...