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FORCES AND FRICTIONNahdir Austin
Honors PhysicsPeriod 2
Forces and Laws of Motion
Force: A push or pull on an object (something that can accelerate objects.
A force is measured by a Newton (N) Newton's First law of Motion: An object will remain at rest or
move with constant velocity when there is no net force acting on it. Also known as the Law of Inertia
Newton's Second Law of Motion: when the net force acting on an object is not zero, the object will accelerate at the direction of the exerted force. The acceleration is directly proportional to the net force and inversely proportional to the mass. Is expressed as the formula F=ma
Newton’s Third Law of Motion: when one object applies a force on a second object, the second object applies a force on the first that has an equal magnitude but opposite direction
Laws of Motion Terminology
Newton: A force that causes an object with a mass of 1 kg to accelerate at 1 m/s is equivalent to 1 Newton
Net Force: sum of all forces acting on an object Action-Reaction Forces: When a force is exerted
on an object the object will exert a force of equal magnitude but opposite directions
Friction
Friction is the force that acts between two object in contact because of action-reaction.
There are two main types of friction, which are static friction and kinetic friction. The static friction force must be overcome by an applied force
before an object can move. Kinetic Friction includes fluid friction and skin friction
Another type of friction includes rolling resistance. Rolling resistance is generally less than that of kinetic
friction due to it’s extremely low values of coefficients of rolling resistance, which are typically about 0.001
Friction Terminology
Normal Force: Any force coming from the surface and acting at a right angle to the surface.
Static Friction: Friction between two solid objects that are not moving relative to each other.
Kinetic Friction: Occurs when two objects are moving relative to each other and rub together
Fluid Friction: The interaction between a solid object and a fluid (liquid or gas), as the object moves through the fluid.
Skin Friction: Force component due to rubbing in fluid dynamics.
Limiting friction: The maximum value of static friction, when motion is impending.
Rolling resistance: The force that resists the rolling of a wheel or other circular object along a surface caused by deformations in the object and/or surface.
Works Cited
http://en.wikipedia.org/wiki/Friction#Static_friction
http://library.thinkquest.org/10796/ch4/ch4.htm
http://www.regentsprep.org/Regents/physics/phys01/friction/normal.htm