ASVAB PHYSICS SECTION

What are the Laws of Thermodynamics?

The Laws of Thermodynamics explain how heat and energy behave. They describe how energy moves and changes but is never destroyed.

What are the Four Laws?

• Zeroth Law

• First Law

• Second Law

• Third Law

Zeroth Law

If A = B and B = C, then A = C (temperature).

• If two objects have the same temperature as a third object, they also have the same temperature as each other.

• This is called thermal equilibrium.

Remember:

Same temp = no heat moves.

First Law

Energy cannot be created or destroyed.

It can only:

• Change form

• Move from one object to another

Examples:

• Electrical → Light

• Chemical → Heat

• Potential → Kinetic

Remember:

Energy never disappears—it just changes clothes.

Second Law

Entropy always increases.

Entropy = disorder or energy that can no longer do useful work.

Also:

• Heat naturally flows
  HOT → COLD
  NOT cold → hot (unless extra work is added).

Examples:

• Ice melts.

• Coffee cools.

• Your room gets messy.

🧠 Remember:

Everything gets messier over time.

Third Law

As temperature approaches Absolute Zero (0 Kelvin)

• Entropy reaches its minimum.

• Absolute Zero cannot actually be reached.

Remember:

You can get REALLY cold—but never perfectly cold.

What is Heat?

Energy moving from one object to another because of a temperature difference.

Heat ALWAYS moves:

🔥 Hot → Cold

Heat is transferred by:

• Conduction

• Convection

• Radiation

HEAT MOVES

What is Temperature?

The average kinetic energy of particles.

The faster atoms move,
the higher the temperature.

Temperature is NOT energy itself.

It is only a measurement.

Measured using:

• Thermometer

TEMPERATURE MEASURES

What is Convection?

Heat transferred by moving liquids or gases.

Examples:

• Boiling water

• Warm air rising

Remember:

Convection = Circulation

What is Radiation?

Heat transferred by electromagnetic waves.

No matter is needed.

Example:

• Sun heating Earth

• Campfire warmth

Remember:

Radiation = Rays

What is Mass?

Amount of matter in an object.

Never changes.

Measured in:

• grams

• kilograms

🧠 Think:
Mass = Matter

What is Weight?

Force of gravity pulling on an object.

Changes depending on gravity.

Example:

• Same mass on Earth and Moon

• Less weight on Moon

• 🧠 Think:
  Weight = Gravity's Pull

Formula for Weight?

Formula:

Weight = Mass × Gravity

What is Volume?

Amount of space an object takes up.

Formula for Volume for a Cube?

V = side³

Formula for Volume for a Rectangular Prism?

V = Length × Width × Height

Formula for Volume for an Irregular object?

Measure by water displacement.

What is Density?

Amount of mass packed into a certain volume.

Formula for Density?

Density = Mass ÷ Volume

(D = m/V)

What happens in High density?

Lots of matter packed tightly.

What happens in Low density?

Matter spread apart.

What is Specific Gravity?

Compares density to water.

If Specific Gravity is Greater than 1 what happens?

Sinks

If Specific Gravity is Less than 1 what happens?

Floats

Formula for Specific Gravity?

Specific Gravity = Density of Object ÷ Density of Water

What is Thermal Contact?

Objects can transfer heat energy between each other.

Direct touching isn't always required.

Eventually,
objects reach

Thermal Equilibrium

What is Thermal Equilibrium?

Where both have the same temperature.

No more heat transfers.

Remember:

Heat always moves until temperatures become equal.

What are the models for the flow of electric charge, and what do they teach us?

Scientists use models (like water and roller coasters) to help explain how electricity moves because electricity itself is invisible.

• Water Model

• Roller Coaster Model

What is the Water Model?

Think of electricity like water flowing through a hose:

• 🔋 Battery = Water pump (creates the push)

• ⚡ Voltage = Water pressure (the push that moves electrons)

• 💡 Current = Water flow (the movement of electrons)

• 🔌 Wire = Hose/Pipe (path the electrons travel)

• ❌ Broken wire = Broken hose (nothing flows)

What is the Roller Coaster Model?

Think of a roller coaster:

• The battery lifts electrons to a higher energy level (like pulling a coaster to the top of a hill).

• At the top, they have potential energy (voltage).

• The electrons then flow downhill through the circuit, just as the coaster rolls downhill.

• If the track is broken, the coaster stops—just like electricity stops if the circuit is open.

Regarding the models of the flow of electric charge, what does Voltage and Current mean?

• Voltage = the PUSH that moves electric charges.

• Current = the FLOW of electric charges.

• Electric charges naturally move from high voltage → low voltage.

• A closed circuit is required for current to flow.

• 🧠 Memory Trick

  "Pump → Pressure → Flow"

  • Battery = Pump

  • Voltage = Pressure

  • Current = Flow

What creates a magnetic field, and what materials are magnetic?

A magnetic field is an invisible area around a magnet or moving electric charge where magnetic forces (attraction or repulsion) can act.

How is a Magnetic Field Created?

Magnetic fields are created when electrons move by:

• Spinning on their axis.

• Orbiting around the nucleus.

These movements make each electron act like a tiny magnet.

What are the Types of Magnetic Materials?

• Ferromagnetic (Strongly Magnetic)

• Paramagnetic (Weakly Magnetic)

• Diamagnetic (Almost Not Magnetic)

What is Ferromagnetic?

These materials are easily attracted to magnets and can become magnets themselves.

Examples:

• Iron

• Nickel

• Cobalt

🟢 Ferromagnetic: Pulls HARD 💪

What is Paramagnetic?

These materials are slightly attracted to magnets because they have some unpaired electrons.

Think: Weak attraction.

🟡 Paramagnetic: Pulls a LITTLE 🤏

What is Diamagnetic?

These materials have paired electrons, so their magnetic effects cancel out.

Think: Little to no attraction.

🔵 Diamagnetic: Doesn't really pull 🙅

What are electric charges?

An electric charge is a property of matter that causes objects to attract or repel one another.

What are the two types of electric charges?

➕ Positive (+)

➖ Negative (−)

What does every charged object create?

ELECTRIC FIELD which is an invisible area around it where it can exert an electric force on other charges.

What charge does Protons have?

Protons have a positive (+) charge.

What charge does Electrons have?

Electrons have a negative (−) charge.

What charge does Neutrons have?

Neutrons have no charge (neutral).

What is Electric Charge?

The property of particles (positive or negative).

What is Electric Current?

The movement (flow) of electric charges.

How do electric charges interact?

Electric charges interact by either attracting or repelling one another.

What is the Rules of Electric Charges?

Opposite charges attract.

• Positive (+) and Negative (−)

Example:
A proton attracts an electron.

What happens to Like Charges?

REPEL

• Positive (+) and Positive (+)

• Negative (−) and Negative (−)

Example:
Two electrons push away from each other.

What does the Electric Force depend on?

• Size of the charges: Bigger charges = stronger force.

• Distance between them: Closer charges = stronger force; farther apart = weaker force.

Where does the Electric field point towards for Positive charges?

➕ Positive charges: Field points away from the charge.

Where does the Electric field point towards for Negative charges?

➖ Negative charges: Field points toward the charge.

What is an electric circuit?

An electric circuit is a complete, closed path that allows electricity (electric current) to flow from a power source, through a device, and back to the power source.

Think of it like a loop that electricity travels through.

What are the Parts of a Simple Circuit?

• Power Source (Battery)

• Wires

• Load (Light bulb, motor, etc.)

• Closed Path

Parts of a Simple Circuit

What does the Power Source (Battery) do?

Provides the voltage (push) that moves electric charges.

Parts of a Simple Circuit

What do the Wires do?

Carry the electric current from one part of the circuit to another.

Parts of a Simple Circuit

What does the Load (Light bulb, motor, etc.) do?

Uses electrical energy to do work (produce light, motion, heat, etc.).

Parts of a Simple Circuit

What does the Closed Path do?

The circuit must be complete for current to flow.

Open vs. Closed Circuit

What does a Closed Circuit mean?

• Complete path

• Electricity flows

• Device works

Open vs. Closed Circuit

What does a Open Circuit mean?

• Broken path

• Electricity cannot flow

• Device does not work

What happens when the electrical loop is broken?

The electricity stops

Why doesn't the light bulb turn on?

The circuit is open (broken).

What is a magnet, and how does it work?

A magnet is an object that creates a magnetic field, allowing it to attract or repel certain materials.

Magnets are especially attracted to ferromagnetic materials, such as:

• Iron

• Nickel

• Cobalt

What materials are Magnets most attracted to?

Ferromagnetic materials

• Iron

• Nickel

• Cobalt

What are the Magnetic Poles?

Every magnet has two poles:

🧭 North Pole (N)

🧭 South Pole (S)

What are the Magnetic Pole Rules?

✅ Opposite poles attract.

(N ↔ S)

❌ Like poles repel.

(N ↔ N)

(S ↔ S)

What are the Types of Magnets?

• Permanent Magnet

• Temporary Magnet

Permanent Magnet

• Keeps its magnetism for a long time.

• Example: Refrigerator magnet.

Temporary Magnet

• Can become magnetic but eventually loses its magnetism.

• Example: Iron nail.

Does a magnet attract every metal?

NO

mainly attracts iron, nickel, cobalt, and some alloys made from these metals.

What are electromagnets and magnetic domains?

An electromagnet is a magnet that is created by electric current.

When electricity flows through a coiled wire, it creates a magnetic field.

If an iron bar is placed inside the coil, the magnetic field becomes much stronger.

What do Electromagnets need to work?

ELECTRIC CURRENT

What are Magnetic domains?

Tiny regions inside a material that must line up for the material to become magnetic.

How can Electromagnets be turned on and off?

By starting or stopping the current.

Before Magnetization

• Domains point in random directions.

• Their magnetic forces cancel out.

• Object is not magnetic.

After Magnetization

• Domains line up in the same direction.

• Their magnetic forces combine.

• Object becomes magnetic.

What is motion?

Motion is the change in an object's position over time.

An object moves when an unbalanced force acts on it.

No unbalanced force = No change in motion.

What can a force make an object do?

• Start moving

• Stop moving

• Speed up

• Slow down

• Change direction

Do balanced forces change motion?

NO

Only unbalanced forces change motion.

Motion = Movement

No movement = No motion.

What is displacement?

Displacement is the straight-line distance and direction from an object's starting point to its ending point.

Unlike distance, displacement includes direction.

What does it mean to be a vector?

• Magnitude (how far)

• Direction

Is Displacement a vector?

YES

What is Distance?

Total path traveled.

Distance = "How far?"

What is gravitational force?

Gravity is the force that pulls all objects toward one another.

The larger an object's mass,
the stronger its gravitational pull.

What does Gravity depend on?

• Mass

• Distance

• More mass = Stronger gravity

• Greater distance = Weaker gravity

What is the Formula for Weight?

Force = Mass × Gravity

F = mg

where

• F = Force (weight)

• m = Mass

• g = 9.8 m/s²

What does Weight depend on?

Gravity

What is Newton's First Law of Motion?

An object at rest stays at rest.

An object in motion stays in motion.

Unless acted on by an unbalanced external force.

First Law = Inertia

What is Inertia?

Inertia is an object's tendency to resist changes in motion.

More mass = More inertia.

What is an example of Inertia?

When a car suddenly stops,

your body keeps moving forward.

What is Newton's Second Law of Motion?

The greater the force, the greater the acceleration.

The greater the mass, the harder it is to accelerate.

What is the Formula for Newtons Second Law of Motion?

F = ma

Force = Mass × Acceleration

What are simple machines?

Simple machines are basic tools that make work easier by changing the size or direction of a force.

They do not create energy.

They only make work easier.

What are the 6 Simple Machines?

• Inclined Plane

• Lever

• Wheel and Axle

• Pulley

• Wedge

• Screw

Simple Machines

What does the Inclined Plane do?

Raises objects with less force.

Simple Machines

What does the Lever do?

Multiplies force.

Example:

Crowbar

Seesaw

Simple Machines

What does the Wheel and Axle do?

Reduces friction and makes movement easier.

Examples:

Doorknob

Bicycle wheel

Simple Machines

What does the Pulley do?

Changes the direction of force.

Makes lifting easier.

Simple Machines

What is the Wedge and what does it do?

Two inclined planes together.

Splits or cuts objects.

Examples:

Knife

Axe

Simple Machines

What is the Screw and what does it do?

Inclined plane wrapped around a cylinder.

Used to hold things together.

What is friction?

Friction is a force that opposes motion when two surfaces touch.

It slows objects down.