A 2kg particle collides elastically with a 4kg particle, and the goal is to determine the maximum deflection of the 2kg particle. To solve this, it's suggested to analyze the collision in the center of momentum frame, where both particles have equal and opposite momentum. The angle of deflection is treated as a variable, and after the collision, the situation is transformed back to the lab frame to find possible angles for the 2kg particle. The discussion emphasizes the importance of showing work and using the appropriate homework template for clarity. The conversation highlights that proper setup can simplify the problem, reducing the number of variables involved.