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