# Graphing Motion Review

Position-time graphs show an object's position (y-axis) versus time (x-axis). Everything you need to know about an object's motion is encoded in the shape and slope of the line.

- The SLOPE of the line = SPEED (rise over run = change in position / change in time) - Steeper line = FASTER speed; gentle slope = slower speed - Flat horizontal line = object at REST (not moving) - Straight line = CONSTANT speed; curved line = CHANGING speed (acceleration) - Line going UP = moving AWAY from starting point; line going DOWN = moving BACK toward start - Where two lines CROSS = two objects at the SAME POSITION at the SAME TIME

### Speed Formula

speed = distance / time (s = d/t)

Example: If an object moves 30 meters in 10 seconds, speed = 30/10 = 3 m/s

# Forces and Newton's Laws

## What Is a Force?

A force is a push or pull on an object, measured in Newtons (N). Forces have both size and direction, making them vectors.

- Net Force: the combined effect of all forces acting on an object - Balanced forces: net force = 0, NO change in motion (object stays still or keeps moving at constant speed) - Unbalanced forces: net force is NOT 0, causes ACCELERATION (speeding up, slowing down, or changing direction)

## Newton's First Law (Law of Inertia)

An object at rest stays at rest. An object in motion stays in motion at the same speed and direction. UNLESS an unbalanced force acts on it.

Inertia = resistance to change in motion. More mass = more inertia.

## Newton's Second Law (F = m x a)

Force = mass times acceleration.

- More force = more acceleration - More mass = less acceleration for the same force - Units: Force in Newtons, mass in kg, acceleration in m/s2

Example: If a 10 kg object has a net force of 50 N, acceleration = F/m = 50/10 = 5 m/s2

## Newton's Third Law (Action-Reaction)

For every action force, there is an equal and opposite reaction force. The two forces act on DIFFERENT objects.

Example: You push on a wall, the wall pushes back on you with equal force.

# Magnetism and Electricity

## Magnets and Magnetic Fields

- A magnetic field is the invisible region around a magnet where magnetic force acts - Every magnet has a North and South pole - Opposite poles ATTRACT (N-S), like poles REPEL (N-N or S-S) - Breaking a magnet in half creates TWO complete magnets, each with N and S poles

## The Discovery That Changed Everything

Hans Christian Oersted (1820) discovered that electric current creates a magnetic field. This showed electricity and magnetism are connected.

## Electromagnets

An electromagnet is a coil of wire wrapped around an iron core, with electric current flowing through it.

Advantages over permanent magnets: 1. Can be turned ON and OFF 2. Strength can be adjusted by changing current or number of coils 3. Poles can be REVERSED by reversing current direction

Applications: electric motors, generators, speakers, MRI machines, maglev trains, junkyard cranes

Key discovery: Electricity produces magnetism, and magnetism can produce electricity (generators).

# Logical Fallacies Quick Reference

| Fallacy | What It Does | Example | |---------|-------------|--------| | Ad Hominem | Attacks the person, not the argument | "You failed math, so your opinion on the budget is worthless" | | Straw Man | Distorts the argument into an extreme version | "You want less homework? So you want students to never learn anything?" | | Red Herring | Changes the subject to distract | "Why worry about pollution when there are potholes on the roads?" | | Bandwagon | Claims it is true because everyone does it | "Everyone is buying this phone, so it must be the best" | | False Dilemma | Presents only two options when more exist | "Either you agree with me, or you do not care about the environment" | | Slippery Slope | Claims one step leads to disaster without evidence | "If we allow phones in class, students will never read books again" | | Appeal to Authority | Uses a famous person without relevant expertise | "This celebrity says the product works, so it must" | | Circular Reasoning | Uses the conclusion as its own evidence | "This is the best school because no school is better" |