Newton's Laws, Force, and Energy Study Notes

Motion is an essential part of daily life explained by Newton's Laws of Motion.
The lesson aims to identify the Three Law’s of Motion and investigate the relationships between force, acceleration, and mass.
Students will observe action-reaction pairs in scenarios like stepping off a boat or a book resting on a table.

Force: A push or pull resulting from interaction with another object. Formula: $F = ma$ . Unit: $N$ (newton).
Motion: Change in an object's position over time relative to a reference point.
Friction: A contact force opposing relative motion between two touching surfaces.
Net Force: The total force acting on an object after all opposing forces are combined or canceled.
Energy: The capacity to do work, measured in Joules ( $J$ ).
Work: The transfer of energy when a force moves an object over a distance ( $W = F \times d$ ).
Gravity: An attractive force pulling objects toward each other; on Earth, it accelerates objects downward at roughly $9\,m/s^2$ .
Mass: The amount of matter in an object, measured in kilograms ( $kg$ ); it remains constant regardless of location.

Free-Body Diagram (FBD): A drawing showing all forces acting on a single object to analyze motion.
Arrows: Represent force direction and magnitude (strength).
Example (Book on Table): The weight ( $W$ ) pulls downward due to gravity, while the normal force ( $N$ ) pushes upward; forces are balanced if the book is stationary.
Example (Pushing a Box): Includes applied force, friction force, weight, and normal force.

Sir Isaac Newton (1642–1727): English mathematician and physicist who formulated the foundation of classical mechanics in 1687.
Key Achievements: Linked gravitational force to planetary orbits and created calculus to prove theories in physics and astronomy.

Definition: Inertia is the natural tendency of an object to resist changes in its state of motion.
Inertia and Mass: It is directly proportional to mass.
Principle: "An object will continue to be in the state of rest or in a state of motion unless an external force acts on it."
Examples: Dust coming off a carpet when shaken; passengers moving forward when a car stops suddenly.

Definition: "The acceleration of an object is directly proportional to the net force acting on it and inversely proportional to its mass."
Direction: Acceleration occurs in the same direction as the net force.
Relationships:
- More force = More acceleration.
- More mass = Less acceleration.
Variables: Acceleration ( $a$ ), initial velocity ( $v_i$ ), final velocity ( $v_f$ ), and time ( $t$ ). Formula: $a = \frac{v_f - v_i}{t}$ .
Examples: Throwing a ball with more strength increases acceleration; an empty shopping cart accelerates faster than a full one.

Principle: "For every action, there is an equal and opposite reaction."
Nature of Forces: Forces always exist in pairs and act on different objects, meaning they do not cancel out.
Examples:
- Walking: Foot pushes backward (action); ground pushes foot forward (reaction).
- Jumping: Person pushes downward (action); ground pushes person upward (reaction).

Setup: Place an index card on a cup with a coin on the card, then flick the card sideways.
Observation: The coin falls into the cup instead of moving with the card.
Guided Questions:
- Why did the coin fall into the cup rather than flying off with the card?
- What property of matter (inertia) causes the coin to stay in place, and how does mass affect it?
- Would a heavier object (e.g., a metal washer) make the activity easier or harder?