Conservation of Linear Momentum in Collisions

Steps:

• Identify initial momentum: only the moving nucleus has momentum along its path; stationary nucleus contributes zero.
• Apply conservation: total momentum vector before equals total after, with no external forces in vacuum.
• Analyze paths: post-collision velocities must sum to initial momentum vector, including zero perpendicular component.
• Check diagrams: impossible if net perpendicular momentum appears post-collision.

Why C is correct:

• In C, both nuclei deflect to the same side, creating net perpendicular momentum, violating conservation of linear momentum (total momentum must remain along initial direction).

Why the others are wrong:

• A: Incident nucleus glances off; target moves forward—momentum vectors balance along initial direction.
• B: Head-on collision; both move forward with reduced speeds—conserves momentum magnitude and direction.
• D: Incident rebounds slightly, target deflects oppositely—perpendicular components cancel, conserving total momentum.

Final answer: C