Offensive/Defensive (Purple Team) Ethical Hacking & Pentesting Notes From the Field Textbook
An in-depth exploration of fundamental ethical hacking and offensive and defensive cybersecurity principles
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Welcome to Offensive/Defensive (Purple Team) Ethical Hacking & Pentesting Notes From the Field Textbook
Welcome to this comprehensive ethical hacking textbook. This interactive resource covers the fundamental principles of cybersecurity from network penetration to malware analysis, providing in-depth explanations, exploit derivations, and practical notes, tips, and examples from the field. powered by blockchain technology. This interactive resource covers the fundamental principles of physics from classical mechanics to modern physics, providing in-depth explanations, mathematical derivations, and practical examples.
Select a topic from the sidebar to begin your exploration of physics concepts. Each section includes detailed explanations, equations, diagrams, and relevant examples to help you understand the principles of physics.
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Start with Classical Mechanics to learn about the fundamental laws of motion, or jump to any section that interests you.
Motion is a fundamental concept in physics that describes the change in position of an object with respect to time. Understanding motion is crucial for developing the foundation of classical mechanics.
Position, Displacement, and Distance
Position refers to the location of an object relative to a reference point. Displacement is the change in position of an object, represented as a vector quantity, while distance is the total path length traveled, which is a scalar quantity.
Displacement (Δx) = Final Position (xf) - Initial Position (xi)
Velocity and Speed
Velocity is the rate of change of displacement with respect to time, making it a vector quantity. Speed, on the other hand, is the rate of change of distance with respect to time and is a scalar quantity.
Average Velocity (vavg) = Displacement (Δx) / Time Interval (Δt)
Instantaneous Velocity (v) = limΔt→0 Δx/Δt = dx/dt
Acceleration
Acceleration is the rate of change of velocity with respect to time. It is a vector quantity that indicates how quickly the velocity of an object changes.
Average Acceleration (aavg) = Change in Velocity (Δv) / Time Interval (Δt)
Instantaneous Acceleration (a) = limΔt→0 Δv/Δt = dv/dt = d²x/dt²
Equations of Motion (Constant Acceleration)
For motion with constant acceleration, the following equations (known as kinematic equations) can be used:
v = v0 + at
x = x0 + v0t + ½at²
v² = v0² + 2a(x - x0)
x = x0 + ½(v0 + v)t
Where v0 is the initial velocity, v is the final velocity, a is the acceleration, t is the time interval, x0 is the initial position, and x is the final position.
Projectile Motion
Projectile motion describes the movement of an object thrown or projected into the air, subject only to the acceleration of gravity. It is a two-dimensional motion where the horizontal and vertical components can be analyzed separately.
Figure 1.1: Projectile motion showing the parabolic trajectory under the influence of gravity
Example: Car Motion
A car accelerates from rest at a constant rate of 3 m/s² for 10 seconds. Find the final velocity and the distance traveled.
Solution:
Given: Initial velocity v0 = 0 m/s, acceleration a = 3 m/s², time t = 10 s
Final velocity: v = v0 + at = 0 + 3 × 10 = 30 m/s
Distance traveled: x = x0 + v0t + ½at² = 0 + 0 + ½ × 3 × 10² = 150 m
Newton's Laws of Motion, formulated by Sir Isaac Newton in the late 17th century, form the foundation of classical mechanics. These three laws describe the relationship between a body and the forces acting upon it, and its motion in response to those forces.
Newton's First Law: Law of Inertia
Newton's First Law states that an object at rest will remain at rest, and an object in motion will remain in motion at a constant velocity, unless acted upon by an external force. This property of objects to resist changes in their state of motion is called inertia.
In mathematical terms, when the net force acting on an object is zero (∑F = 0), there is no acceleration, and the object maintains its current state of motion.
Newton's Second Law: Law of Acceleration
Newton's Second Law states that the acceleration of an object is directly proportional to the net force acting on it, and inversely proportional to its mass. This is often expressed as:
F = ma
or
∑F = m × a
Where F is the net force applied (in newtons, N), m is the mass of the object (in kilograms, kg), and a is the acceleration (in meters per second squared, m/s²).
Newton's Third Law: Law of Action and Reaction
Newton's Third Law states that for every action, there is an equal and opposite reaction. This means that when one object exerts a force on a second object, the second object exerts an equal and opposite force on the first object.
FA on B = -FB on A
Figure 1.2: Newton's Third Law illustrating equal and opposite forces
Applications of Newton's Laws
Free-Body Diagrams
A free-body diagram (FBD) is a simplified representation showing all the external forces acting on an object. Creating an FBD is an essential step in analyzing the motion of objects using Newton's Laws.
Weight and Normal Force
Weight is the force of gravity acting on an object, given by W = mg, where g is the acceleration due to gravity (approximately 9.8 m/s² on Earth). The normal force is the perpendicular force exerted by a surface on an object in contact with it.
Friction
Friction is the force that opposes the relative motion or tendency of motion between two surfaces in contact. The two main types of friction are:
Static Friction (Fs): Acts on objects that are not moving relative to each other, with a maximum value of Fs,max = μsN, where μs is the coefficient of static friction and N is the normal force.
Kinetic Friction (Fk): Acts on objects that are moving relative to each other, given by Fk = μkN, where μk is the coefficient of kinetic friction.
Example: Block on an Inclined Plane
A 5 kg block is placed on a frictionless inclined plane at an angle of 30° to the horizontal. Calculate the acceleration of the block down the plane and the normal force exerted by the plane on the block.
Solution:
Given: mass m = 5 kg, angle θ = 30°, g = 9.8 m/s²
The component of the weight parallel to the incline is m×g×sin(θ).
Acceleration down the plane: a = g×sin(θ) = 9.8 × sin(30°) = 9.8 × 0.5 = 4.9 m/s²
The normal force is perpendicular to the incline: N = m×g×cos(θ) = 5 × 9.8 × cos(30°) = 5 × 9.8 × 0.866 = 42.4 N