[PHY] Chapter 3 - Dynamics

DARRELL ER (COPYRIGHTED) © TOPIC 3: DYNAMICS DARRELL ER (COPYRIGHTED) ©

CHAPTER ANALYSIS THE ABOUT MASTERY EXAM WEIGHTAGE DARRELL ER (COPYRIGHTED) ©

FORCE TYPES OF FORCES NEWTON’S THREE LAW OF MOTIONS KEY CONCEPT DARRELL ER (COPYRIGHTED) ©

FORCE Forces are vector quantities that have both magnitude & direction. Force has the SI unit: Newton (N). 1) Length of arrow represents magnitude of force 2) Direction of arrow indicates direction of force FORCE DARRELL ER (COPYRIGHTED) © 7.0N

Force Symbol Direction of force Diagram Weight W Vertically downwards from center of gravity Tension T Against weight of object / in the direction of the force Normal Reaction N Perpendicular to surface Friction / Air resistance f Against motion of object / body TYPES OF FORCES FORCE DARRELL ER (COPYRIGHTED) © W T f N

NEWTON’S FIRST LAW OF MOTION Newton’s First Law of Motion states that an object at rest will remain at rest and an object in motion will continue in motion at constant speed in a straight line unless a resultant force acts on it. Newton’s First Law is closely associated with the term: inertia. Inertia is defined as the tendency for a body to continue with its state of rest or motion. Inertia is dependent only on the mass of the body. The heavier the body, the larger the inertia, the harder it is for a body to start moving when at rest or changing direction when in motion. NEWTON’S FIRST LAW DARRELL ER (COPYRIGHTED) ©

NEWTON’S SECOND LAW OF MOTION Newton’s Second Law of Motion states that the resultant force acting upon an object is equal to the product of the mass and acceleration of the object, the direction of the force is the same as that of the object's acceleration. Resultant force is defined as the overall force acting on the body after accounting for all forces acting on the body. Formula: F = ma NEWTON’S SECOND LAW DARRELL ER (COPYRIGHTED) © ms-2

NEWTON’S THIRD LAW OF MOTION Newton’s Third Law of Motion states that for every action, there is an equal and opposite reaction. If body A exerts a force on body B, Body B will exert an equal and opposite force on body A. Action reaction forces are: - Equal in magnitude - Act on different bodies - Opposite in direction - Same type of force NEWTON’S THIRD LAW DARRELL ER (COPYRIGHTED) ©

FREE BODY DIAGRAMS VECTOR DIAGRAMS FRICTION KEY CONCEPT DARRELL ER (COPYRIGHTED) ©

FREE BODY DIAGRAM A free body diagram is a diagram which shows all forces acting on the body. FREE BODY DIAGRAMS DARRELL ER (COPYRIGHTED) ©