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UNIT SUMMARY SHEET UNIT04: One Dimensional Dynamics Variables: Symbol: Fnet m a FW FN Ffriction static sliding Name: net force mass acceleration weight normal force frictional force coefficient of static friction coefficient of sliding friction Units: N=kg*m/sec2 kg m/sec2 N N N unitless unitless Equations: Fnet mobject a object Fstatic. friction static FN Fsliding. friction sliding FN Wobject mobject g Concepts: Force – A push or a pull on an object, units are Newtons (N= kg*m/sec2). The net force on an object causes acceleration. Force is a vector quantity (like displacement, velocity, and acceleration). Types of Forces – gravitational, electromagnetic, strong nuclear force, weak force Newton’s Laws of Motion: Newton’s first law – An object with no net force acting on it will remain at rest (if initially at rest) or continue to move with constant velocity in a straight line (if initially moving). Newton’s second law – The acceleration of an object is directly proportional to the net force acting on it and inversely proportional to the object’s mass (Fnet=mobjectaobject). Newton’s third law – When an object exerts a force on a second object, the second object exerts a force on the first object that is equal in magnitude but opposite in direction (action-reaction forces). Special Forces: Weight – The gravitational force exerted on an object due to it’s position near a large celestial body, typically earth. Tension – A rope exerts a pull at each end that is equal to the tension force in the rope. Normal Force – The force pushing two surfaces together (FN). Frictional Force – The force that opposes motion between two surfaces in contact. The force is parallel to the surfaces. Static friction is the force that opposes the start of motion. Sliding friction is the force between two surfaces in relative motion. The frictional force depends upon the normal force and the nature of the surfaces in contact (see equations). Drag Force – The force opposing motion due to friction between a moving object and the surrounding fluid or gas. As velocity increases, so does the drag force. Free-fall objects reach “terminal velocity” when the drag force equals the gravitational force. Problem Solving Strategy for Newton’s Law Problems: Always follow these steps: 1. Identify the object under study 2. Draw a neat picture of the object that includes all forces acting on object (Free Body Diagram) 3. Use Newton’s Laws to answer the question. Mass –A measure of the amount of matter in an object. Mass is unaffected by an objects location. Acceleration – The rate at which an object’s velocity changes with respect to time. Equilibrium – Special name for the condition of an object at rest with all forces balanced. UNIT SUMMARY SHEET