hi every one .. as you can see below on the image on the attachments ,, this is my project paper ... i have already solve 80 % percent of the project ,, but there is one problem that i cant find solution for it ... maybe it is the easiest part ,, but my knowldge on math and movment equations is too bad :)(adsbygoogle = window.adsbygoogle || []).push({});

any way ,, my problem is how can i know the new direction for the particle when it is reach the boundary ( border of the circle ) the direction is represented as angle ,, so how can i know the new angle ( direction ) for a specific particle that is reflected because it is reaching the boundary !!!

sorry my english is not good , but i hope you can at least understand what i mean :)

thanks alot

**Physics Forums | Science Articles, Homework Help, Discussion**

Dismiss Notice

Join Physics Forums Today!

The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

# Homework Help: How to solve This Problem !

**Physics Forums | Science Articles, Homework Help, Discussion**