# Unit 3 Review

### Physics

## Learning Targets

- 3-1. I can describe the ideal conditions applied to the study of forces (ignoring friction).
- 3-2. I can diagram and calculate the horizontal and vertical components of force.
- 3-3. I can explain contact forces on the atomic scale using the particle model.
- 3-4. I can mathematically describe frictional forces.
- 3-5. I can explain and calculate the apparent weight of an object when it’s acceleration is zero
- 3-6. I can apply Newton’s first law of motion to mathematically describe and predict the effects of forces on complex systems of objects.

## Unit 3 Vocab

__Vocabulary__

- component
- equilibrium
- free-body diagram
- forces
- applied
- elastic
- electrostatic
- friction
- gravitational
- net
- normal
- tension
- nuclear
- inertia
- system

## Newton's First Law

- "Law of Inertia"
- "An object at rest will stay at rest unless an outside force act's upon it"
- "An object will stay in motion unless an outside force acts upon it"
- Inertia is the tendency of an object to resist change in velocity.

## Equilibrium

- No acceleration
- All forces are balanced
- Same magnitude and opposite direction

## Free Body Diagrams

- A diagram or model of forces
- Use vectors (arrows) to diagram forces
- Tails of arrows should be connected to other tails
- The object of interest should be labeled as a dot
- The length of the arrows show magnitude and provide direction of force

## Types of Forces

- Fg - Gravity
- Fn - Normal
- Fa - Applied
- Ff - Friction
- Fmag - Magnetic
- Ft - Tension
- Fnet - Net
- Fel - Elastic

## Formulas / Units / Symbols

- SOH-CAH-TOA
- Fnet = F1 + F2 … +Fn
- F2 = Fx2 + Fy2
- Newtons (N)
- 1 N = 1 kg * 1 m/s2