**REVIEW & SUMMARY**

Collisions In a collision, two bodies exert strong forces on each other for a relatively short time. These forces are internal to the two-body system and are significantly larger than any external force during the collision.

Impulse and Linear Momentum Applying Newton’s second law in momentum form to a particle-like body involved in a collision leads to the impulse-linear momentum theorem.

Inelastic Collision One Dimension In an inelastic collision of two bodies. the kinetic energy of the two-body system is not conserved.

Motion of the Center of Mass The center of mass of a closed. isolated system of two colliding bodies is not affected by the collision. In particular.

Elastic Collisions One Dimension An elastic collision is a special type of collision in which the kinetic energy of the system of colliding bodies is conserved.

Collisions in Two Dimensions If two bodies collide and their motion is not along a single axis (the collision is not head on). then the collision is two-dimensional.

### Related Physics Topics for Tuition