1. Forces: Newton’s Laws of Motion Chapters 6 & 7

2.  Any push or pull exerted on an object.  The object is the system  The forces exerted on the system is the environment. Force

3.  Contact: acts on an object by touching it.  Long-Range: exerted without contact. Gravity  Cause of a force is the agent. Contact vs. Long-Range Forces

4.  “An obect that is at rest will remain at rest or an object that is moving will continue to move in a straight line with constant speed, if and only if the net force acting on the object is zero” Sir Isaac Newton  Law of Inertia.  Inertia is the tendency of an object not to accelerate.  Equilibrium: occurs if the net force on an object is zero. Newton’s 1 st Law of Motion

5.  The object is at rest, or moving at a constant velocity.  Net force is anything that disturbs a state of equilibrium  Table 6-2 pg. 123 Newton’s 1 st Law of Motion

6.  A force is needed to keep an object moving.  Inertia is a force.  Air does not exert a force  When an object is thrown, the force of the hand that throws it remains with the object. Force Misconceptions

7.  If an outside force is applied to an object, the object will accelerate.  a= F net/m  Net force is the vector sum of two or more forces on an object.  Weightlessness: no contact forces are acting upon an object. Newton’s 2 nd Law of Motion

8.  Friction is an opposing force acting on an object.  Second force acting in the opposite direction of the applied force on an object.  Static friction: occurs when there is no relative motion.  Kinetic friction: occurs when there is relative motion. Friction

9.  Frictionlike force exerted when an object moves through a fluid.  Force depends on the speed of the motion. Faster the motion, the greater the force. Air Drag

10.  Initially, it has very little velocity and only a small drag force  Gravity is stronger than the upward drag force, so there is downward acceleration  As the object’s velocity increases, so does the drag force.  Drag force will equal force of gravity.  No net force, no acceleration. Velocity becomes constant. Terminal Velocity When dropping an object

11.  Simple harmonic motion: occurs when the force that restores the object to equilibrium is directly proportional to the displacement of the object.  Period: time needed to repeat one complete cycle of motion.  Amplitude: maximum distance that the object moves from equilibrium Periodic Motion

12.  Pendulum: demonstrates periodic motion  Mechanical Resonance: increase in amplitude, occurs when small forces are applied at regular intervals to a vibrating or oscillating object. Periodic Motion

13.  “For every action, there is an equal, opposite reaction”  Interactive forces: two forces that are “equal and opposite”  F A on B = -F A on B Newton’s 3 rd Law of Motion

14.  Gravitational Force  Magnetic  Strong Nuclear Force  Weak Nuclear Force Four Fundamental Forces