## 1. Collisions

### 1.1. Completely Inelastic

1.1.1. “Perfect Sticking”

1.1.2. Conservation of only momentum

1.1.3. m1v1i +m2v2i = (m1 +m2 )vf

### 1.2. Inelastic

1.2.1. “Sticky” but the bodies do not stick together

1.2.2. Conservation of momentum only

### 1.3. Elastic

1.3.1. “Perfect bouncing”

1.3.2. Conservation of kinetic energy and momentum

1.3.3. m1v1i +m2v2i = m1v1f +m2v2f

## 2. System of Particles

### 2.1. Center of Mass

2.1.1. Average location of the mass in a system of particles

2.1.2. 3D in general

2.1.3. Motion of the Center of Mass

2.1.4. Isolated system moves at a constant velocity

## 3. Problem solving: Collisions

### 3.1. Draw before and after diagrams

### 3.2. Collect and organize data on masses and velocities

### 3.3. Set the sum of momenta of the two before the collision = to the sum of the momenta after the collision

### 3.4. Write one equation for each direction

### 3.5. If perfectly inelastic set final velocities equal

### 3.6. If perfectly elastic set final kinetic energy equal to initial kinetic energy

### 3.7. Solve for unknown quantities

## 4. Words of the Day

### 4.1. Transpicuous

### 4.2. Trust

### 4.3. Woolgathering

### 4.4. Applicability

## 5. Linear Momentum

### 5.1. vector Quanity having same direction as the velocity

### 5.2. The vector of p = mass times the vector of velocity

### 5.3. The momentum and changes of two objects are always equal and opposite

## 6. Momentum

### 6.1. Vector quanity

### 6.2. For momentum to be Conserved these things must be constant

6.2.1. Magnitude

6.2.2. Direction

### 6.3. Mass and velocity involved

### 6.4. Conservation

6.4.1. If no external force acts on system, the initial momentum of the system is equal to the final momentum of the system.