Chapter 1 - About Science

1.2 Scientific Methods

The scientific method is a systematic approach used to investigate phenomena, acquire new knowledge, or correct and integrate previous knowledge. It relies on observation, experimentation, and logical reasoning.

• Scientific method: A process involving observation, hypothesis, experimentation, and conclusion.

• Fact, law, principle, theory:

  • Fact: An observation that has been repeatedly confirmed.

  • Law: A statement based on repeated experimental observations that describes some aspect of the universe.

  • Principle: A fundamental truth or proposition serving as the foundation for a system of belief or behavior.

  • Theory: A well-substantiated explanation of some aspect of the natural world.

• Science involves being able to potentially prove something wrong (falsifiability).

1.3 Science, Art, and Religion

Science, art, and religion represent different ways of understanding and interpreting the world.

• Science is just one way of finding truth, focusing on empirical evidence and testable explanations.

Chapter 2 - Newton's First Law of Motion - Inertia

2.2 Galileo's Experiments

Galileo Galilei conducted experiments that challenged the prevailing views on motion, laying the groundwork for Newton's laws.

• Galileo observed that without friction, objects move at a constant velocity.

• Inertia: The apparent resistance of an object to changes in its state of motion (e.g., velocity).

2.3 Newton's First Law of Motion

Newton's First Law, also known as the Law of Inertia, states that an object at rest remains at rest, and an object in motion remains in motion at constant velocity unless acted upon by a net external force.

• Every object maintains its current velocity unless acted on by a net external force.

• Inertia: The tendency of objects to resist changes in motion.

2.4 Net Force and Vectors

Forces are vector quantities, meaning they have both magnitude and direction. The net force is the vector sum of all forces acting on an object.

• Net force: The sum of all forces acting on an object.

• Vectors: Quantities with both magnitude and direction.

2.5 The Equilibrium Rule

An object is in equilibrium when the net force acting on it is zero.

• When net force is zero, there is no change in velocity.

• Equilibrium can be static (at rest) or dynamic (moving at constant velocity).

2.6 Support Force

The support force is the upward force that balances the weight of an object resting on a surface.

• A table or bathroom scale provides an upward support force to keep us from falling.

• Also known as a normal force.

Chapter 3 - Linear Motion

3.1 Speed

Speed is a measure of how fast an object is moving, defined as the distance traveled per unit time.

• Speed = change in position

• Speed is a scalar quantity (has magnitude only).

3.2 Velocity

Velocity is a vector quantity that describes both the speed and direction of an object's motion.

• Velocity = change in position per unit time, with direction.

• ("The east")

• Units: meters per second (m/s).

• Average velocity:

• Instantaneous velocity:

3.3 Acceleration

Acceleration is the rate at which velocity changes with time.

• Acceleration = change in velocity / time

• Units: meters per second squared (m/s2).

3.4 Free Fall

Objects in free fall experience the influence of gravity only, accelerating downward at a constant rate.

• The acceleration due to gravity is (often approximated as ).

• Velocity after time :

• Distance fallen after time :

• There is a square relationship between distance and time.

Chapter 4 - Newton's Second Law of Motion

4.1 Forces

A force is any influence that causes a change in motion (i.e., velocity). Acceleration is proportional to force.

• Force causes acceleration.

4.2 Friction

Friction is a force that acts to resist the relative motion (or attempted motion) of objects in contact.

• Friction acts in the direction opposite to the relative motion.

• It depends on the nature of the surfaces and the force pressing them together.

4.3 Mass and Weight

Mass is the quantity of matter in an object, while weight is the force upon an object due to gravity.

• Mass is measured in kilograms (kg).

• Weight is measured in newtons (N).

• Weight formula:

• The unit for force is newtons (N), which is the same as kilogram meter per second squared ().

4.4 Newton's Second Law of Motion

Newton's Second Law relates force, mass, and acceleration.

• More force results in more acceleration.

• More mass results in less acceleration for the same force.

4.5 When Acceleration is g - Free Fall

In free fall, all objects under the influence of gravity only accelerate at the same rate, regardless of mass.

• Acceleration due to gravity:

• Objects of different mass fall at the same rate (ignoring air resistance).

4.6 When Acceleration is Less than g - Nonfree Fall

When air resistance matters, objects fall at a rate less than .

• Heavier objects have more weight and can overcome air resistance more easily.

• Objects reach terminal velocity when the upward force of air resistance equals the downward force of gravity.

Chapter 5 - Newton's Third Law of Motion

5.1 Forces and Interactions

Newton's Third Law states that forces always occur in pairs as part of an interaction.

• Every force is part of an interaction.

5.2 Newton's Third Law of Motion

For every action, there is an equal and opposite reaction.

• Force comes in pairs.

• For every interaction, the forces are equal and opposite.

5.3 Action and Reaction on Different Masses

Action-reaction pairs act on different objects, and the effect depends on the mass of each object.

• Every acceleration pair occurs on different objects.

• The same magnitude of force affects each object differently based on its mass.

• Newton's Second Law:

5.4 Vectors and the Third Law

Vectors can be broken into components and combined into a resultant vector.

• Every vector can be broken into its components.

• Components can be combined into a resultant vector.