Physics · Ch 4 — Laws of Motion
Collisions
Collisions
A COLLISION is an interaction in which two or more objects come close, exert mutual forces on each other for a brief interval, and then move apart (scatter) in generally different directions/speeds than before. Crucially, during a collision the forces the colliding bodies exert on EACH OTHER are INTERNAL forces for the system consisting of all the colliding bodies together -- so, exactly as the conservation principle of section 4.7 requires, the TOTAL linear momentum of the whole system of colliding particles is always conserved during a collision (or an explosion), , even though the individual momentum of each separate particle does change due to these mutual internal forces. Whether the total …
What this figure shows. A three-part sequence of simple schematic diagrams showing a head-on (one-dimensional) collision between two bodies drawn as blocks or discs moving along the same straight horizontal line. Part (a) 'before collision' shows the two bodies approaching each other along the line, each with a velocity arrow pointing toward the other (their initial velocities u1 and u2, moving towards contact). Part (b) 'during impact' shows the two bodies in contact/overlapping at the moment of collision, illustrating the brief interval when the mutual (internal) contact force acts between them along the line of motion. Part (c) 'after collision' shows the two bodies now separated again along the same line, each with a new velocity arrow (v1 and v2) which may point in the same or opposite directions depending on whether the lighter body rebounds; no numeric values are printed, the figure is purely schematic to define the geometry …