## Chapter 2-Forces

by Melissa Schultz
## 1. Vectors

### 1.1. magnitude and direction

### 1.2. can be used to find net force

### 1.3. Examples: weight, velocity, force

### 1.4. measured using two methods

1.4.1. Polar method: descriptive, vector arrow with angle to horizontal

1.4.2. Step method: x hat and y hat, make triangle of x and y components, use SOH CAH TOA

### 1.5. arrows drawn tip to tail

## 2. Measurements

### 2.1. Newtons = kg * m/s^2

### 2.2. Weight = mass * gravitational field strength

### 2.3. mass = kg

### 2.4. average g (gravitational field strength) on earth = 9.80 N/kg

## 3. Newton's Laws

### 3.1. 1. Inertia - object moves until forces change its movement, or at rest till forces move it

3.1.1. Equilibrium

3.1.1.1. moving at constant speed and direction

3.1.1.2. staying at rest

### 3.2. 2. Force vector = mass scalar * acceleration vector

### 3.3. 3. For every action, there is an equal and opposite reaction; within an interaction pair of 2 objects

3.3.1. Internal forces

3.3.2. External forces

## 4. Field Forces

### 4.1. Gravitational

4.1.1. Newton's Law: any two objects exert gravitational forces on each other that are related to distance and mass

4.1.1.1. F = G*m1*m2 / r^2

4.1.1.2. G = universal gravitational constant

### 4.2. Electromagnetic

### 4.3. Strong

### 4.4. Weak

## 5. Contact Forces

### 5.1. Normal

### 5.2. Friction

5.2.1. Kinetic

5.2.2. Static

### 5.3. Tension

5.3.1. ideal pulley or cord

5.3.2. typically studied in biomechanics

## 6. Free Body Diagrams: show all forces on object

### 6.1. can be drawn and measured using vectors

## 7. Lab

### 7.1. Distance and time

### 7.2. Velocity and time

## 8. Blogs

### 8.1. Hurricane forces

### 8.2. Earthquake forces