1350Kg tuned up Civic moving at 15m/s hits a 1450Kg car moving at 12m/s

[DrVirus]

Im not really good at elastic and inelastic collisions,, can someone help me with collisions please.

In the movie the fast and the furious, a 1350Kg tuned up Civic moving at 15m/s hits a 1450Kg car moving at 12m/s. Determine the final velocity of the cars if (a) the collision was elastic AND (b) the collision was inelastic.

THank you for any help you can give.

 

[arcnets]

DrVirus,
you have 2 unknowns (the final velocities).

In an elastic collision, both momentum and kinetic energy are conserved. So 2 equations, fine.

In an inelastic collision, only momentum is conserved. To get the 2nd equation, you usually assume that the bodies stick together after collision.

 

[DrVirus]

Well, its been an hour since i posted the question. I got the first part for elastic collision right.. but the inelastic i can't solve it, can someone show me how to solve it, because then tomorrow i have a lab that has to do with collisions and i have to understand this. Thanks a lot

 

[arcnets]

As I said:
Momentum: p_final=p_initial
Sticking: v_1,final=v_2,final=:v_final
=>
(m₁+m₂)v_final=p_initial

You have calculated p_initial in part (a), haven't you?

 

[DrVirus]

No, i didnt solve for Pi. i used an equation that works with elastic collision only and has to have V2 as 0. so i change the frame of reference to be 0, and changed it back after i got the answer.

 

[arcnets]

p_initial=m₁v_1,initial+m₂v_2,initial

Just plug in.