Module-2-Phys

Course Title and Overview

• Course Title: Physics for Engineers

• Year Level: BSGE 1

• Time Frame: 6 hours/week

• Unit Title/Chapter Title: Chapter 1 - Basic Concept of Dynamics

• Desired Learning Outcomes:

  • Identify the concepts of Dynamics

  • Discuss Newton’s Law of Motion: Force and Motion

  • Apply Newton’s Laws in various scenarios

I. Dynamics Fundamentals

• Definition: Dynamics is the study of how forces affect the motion of objects.

• Force: A push or pull that has both magnitude and direction; it is a vector quantity.

• External Forces: Forces acting on a body from outside; represented through a free-body diagram showing all external forces.

II. Newton’s Laws of Motion

A. First Law of Motion: Inertia

• Statement: A body at rest stays at rest, and a body in motion remains in motion at a constant velocity unless acted upon by a net external force.

• Inertia: Tendency of an object to maintain its state of rest or motion; related to mass.

• Mass: Quantity of matter in a substance.

B. Second Law of Motion: Concept of a System

• Acceleration: Change in velocity (magnitude or direction).

• External Forces: Act on a system from outside; internal forces act between components within a system.

• Law Statement: Acceleration (a) of a system is directly proportional to the net external force (F_net) and inversely proportional to its mass (m).

• Equation:

  • [ F_{net} = ma ]

• Weight (w): Force due to gravity acting on an object of mass (m); [ w = mg ]

• Free Fall: When only gravity acts on an object.

• Friction: A force opposing motion of touching objects.

C. Third Law of Motion: Action-Reaction Principle

• Statement: For every action, there is an equal and opposite reaction; forces always occur in pairs.

• Example: Thrust generated by rockets, airplanes, and cars is a reaction force that propels the vehicle forward.

III. Types of Forces

• Weight (W): Gravitational force acting downward.

• Normal Force (N): A perpendicular force from a surface reacting to an object’s weight.

• Sliding Friction: Opposes motion between sliding surfaces.

  • Static Friction (f_S): Prevents the start of motion.

  • Kinetic Friction (f_K): Opposes the motion of moving objects.

• Tension (T): Force exerted by a cord, cable, or rope when it is pulled.

IV. Equilibrium and Motion

A. First Condition of Equilibrium

• Equilibrium: When net force acting on an object is zero, resulting in constant velocity.

  • Static Equilibrium: Object at rest.

  • Dynamic Equilibrium: Object in uniform motion.

B. Application of Newton’s Laws in Problem Solving

1. Draw a sketch of the problem and identify known/unknown quantities.

2. Create a free-body diagram (FBD) showing forces acting on the object.

3. Apply Newton’s second law in horizontal and vertical directions and analyze forces.

4. Ensure the reasonableness and correctness of your answer.

V. Newton’s Law of Gravitation

• Gravitation Concept: Objects attract each other due to their mass.

• Gravity Calculation Near Earth: Force of gravity experienced by objects is based on Earth’s mass and distance from its center.

• Newton’s Shell Theorem: A uniform shell exerts no net gravitational force on a particle located inside it.