Advanced Physics Chapter 4 Motion and Force: Dynamics

Chapter 4 l 4-1 Force l 4-2 Newton’s First Law of Motion l 4-3 Mass l 4-4 Newton’s Second Law of Motion l 4-5 Newton’s Third Law of Motion l 4-6 Weight-the Force of Gravity and the Normal Force l 4-7 Solving Problems with Newton’s Laws l 4-8 Applications Involving Friction and Inclines l 4-9 Problem Solving

4-1 Force l Force a push or a pull

4-2 Newton’s First Law of Motion l Newton’s First Law of Motion l Net Force Vector sum of all forces acting on an object l Inertia Tendency of a body to maintain its state of motion

4-2 Newton’s First Law of Motion l Inertial vs. non-inertial reference frames a

4-3 Mass l Mass vs. Weight

4-4 Newton’s Second Law of Motion l Newton’s Second Law of Motion l Force An action capable of accelerating an object (N) l equation:  F = ma

4-5 Newton’s Third Law of Motion l Newton’s Third Law of Motion

4-5 Newton’s Third Law of Motion l Net Force l Action-Reaction Force

4-6 Weight-Force of Gravity and Normal Force l Weight (F g ) Force of gravity on an object l Contact Force l Normal Force (F n ) Contact force that acts perpendicular to the surface of contact l Are F g and F n action-reaction forces?

Does anyone remember the five forces equation? (4-7)

4-7 Solving Problems with Newton’s Laws l Free-Body (force) diagram Five forces l Tension The force exerted when a flexible cord pulls on an object

4-7 Solving Problems with Newton’s Laws Problem solving: l If 150 N of upward force is applied to a 35 kg object calculate its rate of acceleration 150 N

4-8 Applications involving Friction, Inclines l Kinetic (sliding) Friction Friction that opposes the motion of two objects in contact and in relative motion

4-8 Applications involving Friction, Inclines l Static Friction Friction that opposes the motion of two objects in contact and NOT in relative motion

4-8 Applications involving Friction, Inclines l Coefficient of friction (  ) Depends on the nature of two surfaces  = F f  F n ROT  s >  k

4-8 Applications involving Friction, Inclines Inclined Planes l Find the force of friction that acts on a 35 kg box that sits on a 25  inclined plane.

4-8 Applications involving Friction, Inclines Inclined Planes l Find the force of friction that acts on a 35 kg box that sits on a 25  inclined plane. l Answer: 145N

4-9 Problem Solving-A General Approach Do Your Homework