forces+and+newton+laws

__Forces & Newton Laws__

1st law-**an object at rest remains at rest, and an object in motion continues in motion with constant velocity unless the object experiences net external force** -inertia; //the tendency of an object to resist being moved, or if the object is moving, to resist a change in speed or direction// -2 examples of 1st law; //a block moving on carpet will stop moving if no force is applied as opposed to a block sliding on smooth surface going forever// 2nd law-**force is proportional or directly affected by the mass and acceleration of an object F=ma (force=mass * acceleration)** -net force (two definitions); //sum of all individual forces acting on an object// -force diagram -difference between weight and mass; //weight is affected by the acceleration of gravity and is dependent on where an object is while mass is always the same and is not affected by vectors// 3rd law-**for every action there is an equal and opposite reaction** -normal force; //force that acts on a surface in a direction perpendicular to the surface// -action/reaction pairs; //driving a nail into wood, the hammer exerts force on the nail and the nail reacts with equal and opposite reaction/ punching a wall you are exerting an action on the wall with your hand and the wall has an equal and opposite reaction on your hand// -friction; //force that resists motion of an object// -coefficient of friction; //ratio of the magnitude of the force of friction between two objects in contact to the magnitude of the normal force with which the objects press against eachother (represented by the greek symbol "mu")// -two things friction depends on?; //composition and quality of objects (for example it is easier to slide an object on tile than on carpet)// -kinetic vs static friction; //static friction is when two surfaces that are in contact will cause one of the surfaces that is accelerating to slow down and come to rest (resists the motion) kinetic friction works less on an object and is the force that resists objects movement when they slide over eachother//