The way to solve it depends on what is the purpose of your simulation.

For the case you provided above:
Yes. in theory (mathematically), the first ball will collide with the other two ball at the same time.
If you really need such precission: The above problem can be solve analytically.

However, in real case, there is always a small error. The first ball wil hit one of them first, then collide with the second one. You can check out [url=]Collision 2D[/url] to find out how to calculate collision between two balls.
The same technique was used to calculate collision between many particles: [url=]Browian motion.[/url] or [url=]particle model of liquid in a container (microscopic)[/url]

If you need a better time precission, EJS has build in EVENT GUI interface to help you.

Select one of the experiment (other than the default: Random)
Click Pause to hold the simulation, then drag one of the ball a very small amount and click play again.
You can modify value of g to add gravity or change k for inelastic collision.
You will find it really calculate all the collisions between particles.

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