Impact
Impact
Impact: When two bodies collide over a very small interval of time and exert relatively large forces on one another. A good example of impact is the game of billiards.
![](partmo_impact_fig1.png)
There are two axes that, if identified, may simplify the analysis of the system of colliding particles.
- Line of impact: The line drawn between the centers of mass of the two bodies that passes through the contact point.
- Plane of contact: Perpendicular to the line of impact and resides at the contact between the two bodies.
![](partmo_impact_fig2.png)
Coefficient of restitution
Energy is generally not conserved during impact (inelastic). Energy is lost due to …
- Plastic material deformation
- Heat
- Sound
If the bodies stick together after the impact, it is perfectly inelastic. If energy is conserved, the impact is perfectly elastic.
A measure of the elasticity of a collision is its coefficient of restitution.
- e = 0 (perfectly elastic)
- e = 1 (perfectly inelastic/plastic)
Name examples of impacts that are nearly perfectly elastic and perfectly inelastic.