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Published byAmberly Harvey Modified over 9 years ago
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Unit IV: Force Forces in Static (Non-Moving) Situations Per. 3, 6
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Force: What is it? Force is an interaction between two objects Force is an interaction that can have an effect on the motion of an object Has units of Newtons (N)
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Consider the Rock below:
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Notes on: Friction Force Static Friction, F fs, is a friction force exerted by a surface that prevents an object from moving. Friction always OPPOSES motion – Friction never causes an object to move, it only resists motion Friction is always directed parallel to the surface.
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Notes on: Normal Force Normal Force, F N, is the force exerted perpendicularly by a surface. Normal Force is a reaction force; – It arises from the atoms or molecules in the surface pushing back, whenever they are pushed upon. “Normal” is Math-speak for “Perpendicular” Normal Force is always perpendicular to the surface.
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Notes on: Tension Force Force exerted along the length of an object, most commonly a rope, chain or string Tension can be exerted by a rigid object (example, the handle of a wagon) Tension is exerted along the length of the rope, string or chain. Tension can be redirected by a pulley, it always goes the way the rope is going For purposes of this class, Tension is constant within a rope, string or chain.
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Drawing Force Diagrams Identify a system (draw dotted line around the object that will be your system) Identify every force acting on the system Draw a Force vector arrow for every force – Vector goes in direction that force acts on the object – Magnitude represents relative strength – Label Force, F N, F g, F fs, etc. – Identify using “on-by”: F N on apple by floor
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Half of Newton’s First Law If an object is at rest, the Forces acting on that object are balanced – How can we judge whether forces are balanced?
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Remember: Friction Force parallel to surface, opposes motion Normal Force perpendicular to the surface that is exerting the force Tension Force along the length of the rope or string.
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