Find the Velocity of car A before the collision?

[theemassive1]

Bumper cars A and B each have a mass of 100 kg. Bumper car A collides ealstically with bumper car B, which is at rest. After the Collision, the velocity of car A is 0.8 m/s 30degress north of east and car B is 0.6 m/s 60degrees south of east.

1 Find the Velocity of car A before the collision?
2. How would the problem change in the collision were inelastic?


can sum1 please tell me where to even begin here, I am completely lost.

 

[quasar987]

Hi, theemassive1! Welcome to PF. Please note that there is a sub-forum especially for homework help. See https://www.physicsforums.com/forumdisplay.php?f=35 . (But don'r repost there, the moderators will move your thread if they feel the need.)

What you've got here is a conservation of momentum problem. The core equation is

$$\sum_{k=A}^B \vec{p}_k^{initial} = \sum_{k=A}^B \vec{p}_k^{final}$$

where the $\vec{p}_k^{initial}$ are the momentum vectors of the bumber cars right before the collision, and the $\vec{p}_k^{final}$ are the momentum vectors of the bumber cars right after the collision. So after you've set up this equation and chosen a practical coordinate system (the standart is to take the y-axis pointing south), the physics is over and all that remains to do is sort out the math: you know how to add vectors and you know that vectors are equal iff their components are equal. So solve for the unknowns: the x and y components of the velocity of A before collision.

 

[theemassive1]

ok, i got it now, thanks a lot