Math help...

[HungryDragon]

I'm not one for math help, considering I usually get this stuff. It's been more than a year since I've taken a real math course of any kind.

The question I have right now is if I manipulated the following formula correctly:

P_t +m_cv_c= P_t^' + m_c^'v_c^'

to isolate for m_c

NOTE: In this case m_c and m_c^' are the same value

m_c = P_t^' - P_t^'
      -------
       v_c - v_c^'


EDIT: vector  conventions are needed, but no such characters exist *sigh*
       
       
                     
                       

[Jamaha]

m_c = P_t^' - P_t
      -------
       v_c - v_c^'      

[Harvest]

~head explodes~

[HungryDragon]

~head explodes~

Physics tends to do that to you sometimes. I've already cleaned up of few of those this year, and we're not even one month in

[blah54]

ok... i'm assuming this is momentum, cause my formula doesn't look exactly like that, but similar...

so... ya, you could find the mass that way, use what jamaha wrote, you've written two final momentums, when there should be one final and one initial...

but since the mass didn't change, you could technically just use
p = mv for either the initial or final momentum and isolate for m that way...

[HungryDragon]

ok... i'm assuming this is momentum, cause my formula doesn't look exactly like that, but similar...

so... ya, you could find the mass that way, use what jamaha wrote, you've written two final momentums, when there should be one final and one initial...

but since the mass didn't change, you could technically just use
p = mv for either the initial or final momentum and isolate for m that way...

It is a collision. Law of Conservation of Momentum.

Maybe I should have specified that. The mass of the truck was given as well as the velocities of the truck and car before and after the collision. The velocities for each were diferrent from before and after the crash. So, according to LoCoM, ΣP_before = ΣP_after So in short, the total (Σ) momentum would remain constant, but the momentum for each object would change

eg.

P₁ + P₂ = P₁^' + P₂^'

500kg*m/s + 500kg*m/s = 750kg*m/s + 250kg*m/s

All I wanted was clarification on whether or not I manipulated the formula correctly or not, as I was a little out of practice on the factoring part.

[WiiMan96]

~yet another head explodes from Grade 7 simplicity~

[Palagerini]

wait what happened to mc' in your equation? it's the same value  as mc right? so how did u get rid of it?

[Jamaha]

Pt + McVc = Pt' + Mc'Vc' | Mc' = Mc
McVc - McVc' = Pt' - Pt
Mc(Vc - Vc') = Pt' - Pt | : (Vc - Vc')
Mc = (Pt' - Pt) / (Vc - Vc')

No getting rid of anything.

[HungryDragon]

wait what happened to mc' in your equation? it's the same value  as mc right? so how did u get rid of it?

Mc' in this case was the same value of Mc. I didn't get rid of it, it just got factored out here. I guess I like to differentiate between before and after the collision ^^;

McVc - McVc' = Pt' - Pt
Mc(Vc - Vc') = Pt' - Pt

[Palagerini]

ah ok that makes sense.. i'm only in geometry =P.