Collisions involve forces (there is a change in velocity). Collisions can be elastic, meaning they conserve energy and momentum, inelastic, meaning they conserve momentum but not energy, or totally inelastic (or plastic), meaning they conserve momentum and the two objects stick together.
The magnitude of the velocity difference at impact is called the closing speed.
The field of dynamics is concerned with moving and colliding objects.
Consider an elastic collision in 2 dimensions of any 2 masses m1 and m2, with respective initial velocities v1 in the x-direction, and v2 = 0, and final velocities V1 and V2.
Conservation of momentum: m1v1 = m1V1+m2V2.
Conservation of energy for elastic collision: 1/2m1|v1|2 = 1/2m1|V1|2+1/2m2|V2|2
Now consider the case m1 = m2, we then obtain v1=V1+V2 and |v1|2 = |V1|2+|V2|2
Using the dot product, |v1|2 = v1•v1 = |V1|2+|V2|2+2V1•V2
So V1•V2 = 0, so they are perpendicular.
An attacking collision with a distant object can be achieved by throwing or launching a projectile.
Collisions of Cloud Droplets in a Turbulent Flow. Part V: Application of Detailed Tables of Turbulent Collision Rate Enhancement to Simulation of Droplet Spectra Evolution
Feb 01, 2008; ABSTRACT The present study is a continuation of the series of studies dedicated to the investigation of cloud droplet...