Physics Chapter 5: Newton's Laws and Friction

First Law (Law of Inertia):
- An object at rest stays at rest, and an object in motion remains in motion at a constant velocity unless acted on by a net external force.
- Inertia is the tendency of an object to resist changes in its state of motion.
Second Law (Law of Acceleration):
- The acceleration of an object is directly proportional to the net force acting on it and inversely proportional to its mass.
- Formula: ( F = ma ) (Force = mass × acceleration)
Third Law (Action-Reaction):
- For every action, there is an equal and opposite reaction.
- Forces always occur in pairs; if object A exerts a force on object B, then object B exerts an equal force in the opposite direction on object A.

Definition: A force that opposes the relative motion of two surfaces in contact.
Types of Friction:
- Static Friction: Prevents motion between static surfaces.
- Kinetic (Sliding) Friction: Acts on moving surfaces.
- Rolling Friction: Resistance encountered when an object rolls over a surface.
Factors Affecting Friction:
- Surface roughness: Rougher surfaces increase friction.
- Normal force: Greater normal force (weight) increases frictional force.
Friction Formula: ( F_f = \mu F_n )
- Where ( F_f ) is the frictional force, ( \mu ) is the coefficient of friction, and ( F_n ) is the normal force.

Definition: A measure of the motion of an object, defined as the product of its mass and velocity.
Formula: ( p = mv ) (Momentum = mass × velocity)
Conservation of Momentum: In a closed system, the total momentum before an event is equal to the total momentum after the event.
Types of Collisions:
- Elastic Collisions: Total kinetic energy and momentum are conserved.
- Inelastic Collisions: Momentum is conserved, but kinetic energy is not.

Definition: The property of matter that causes it to resist changes in its state of motion.
Relationship to Mass: Greater mass equates to greater inertia, meaning heavier objects require more force to change their motion.
Practical Examples:
- A stationary object will not move unless a force is applied.
- A moving object will not stop or change direction unless acted upon by an external force (e.g., friction).

First Law (Law of Inertia): Objects maintain their state of motion unless influenced by an external net force; inertia keeps objects at rest or in constant motion.
Second Law (Law of Acceleration): Acceleration is proportional to net force and inversely proportional to mass, expressed as ( F = ma ).
Third Law (Action-Reaction): Forces occur in pairs; if object A exerts a force on object B, B will exert an equal and opposite force on A.

Definition: A force opposing relative motion between contact surfaces.
Types of Friction:
- Static Friction: Prevents the start of motion between static surfaces.
- Kinetic (Sliding) Friction: Acts on surfaces in motion against each other.
- Rolling Friction: Resistance encountered by rolling objects.
Factors Affecting Friction:
- Surface roughness increases friction; rougher surfaces create more resistance.
- Greater normal force (weight) elevates frictional force.
Friction Formula: ( F_f = \mu F_n ) where ( F_f ) = frictional force, ( \mu ) = coefficient of friction, ( F_n ) = normal force.

Definition: Measure of an object's motion, calculated as the product of mass and velocity, expressed as ( p = mv ).
Conservation of Momentum: In a closed system, total momentum remains constant before and after an event.
Types of Collisions:
- Elastic Collisions: Both kinetic energy and momentum are conserved.
- Inelastic Collisions: Momentum is conserved, but kinetic energy is not.

Definition: The tendency of matter to resist changes in motion; related to the mass of the object.
Relationship to Mass: Higher mass leads to greater inertia, requiring more force to change motion.
Practical Examples:
- Stationary objects need an external force to move.
- Moving objects will continue in motion or stop only when acted upon by external forces such as friction.

Definition: Represents how electrons are arranged within an atom's orbitals for determining chemical properties.
Principle Quantum Number (n): Indicates the shell level where electrons reside; higher n values correspond to higher energy levels.
Aufbau Principle: Electrons occupy the lowest available energy orbitals before filling higher ones.
Pauli Exclusion Principle: Ensures that each electron in an atom has a unique set of four quantum numbers, enforcing electron differentiation.
Hund's Rule: Electrons fill degenerate orbitals one at a time before pairing, minimizing electron-electron repulsion.
Notation:
- Orbital Notation: Visual representation using arrows to show electrons in orbitals.
- Electron Configuration Notation: Describes electron arrangement, e.g., Neon: 1s² 2s² 2p⁶.
- Noble Gas Notation: Shortened form for electron configurations, e.g., Magnesium: [Ne] 3s², highlighting core electron configuration.

Types:
- Protons: Positively charged, reside in the nucleus, and define an element's atomic number.
- Neutrons: Carry no charge, also located in the nucleus, and contribute to the overall atomic mass.
- Electrons: Negatively charged particles located in orbitals outside the nucleus, crucial for chemical bonding and reactions.
Mass:
- Protons and neutrons each have a mass approximately 1 atomic mass unit (amu).
- Electrons have a negligible mass, roughly 1/1836 of a proton.
Charge:
- Protons have a charge of +1.
- Neutrons have no charge (0).
- Electrons have a charge of -1.

Dalton's Model: Describes atoms as indivisible and identical within each element, laying groundwork for atomic theory.
Thomson's Model (Plum Pudding Model): Suggests a uniform sphere of positive charge with negatively charged electrons scattered, like plums in pudding.
Rutherford's Model: Introduced a dense, positively charged nucleus surrounded by electrons, leading to the concept of atomic structure.
Bohr Model: Proposes that electrons orbit the nucleus in defined pathways or energy levels, with quantized energy states.
Quantum Mechanical Model: Describes electrons as residing in probability clouds or orbitals, integrating wave-particle duality and quantum mechanics to explain electron behavior.