Forces+and+Newton's+Laws

Inertia is the tendency of the object to resist being moved or, if the object is moving, to resist a change in speed or direction. When a car is at rest, and is rear-ended, the passenger's body is pushed forward, while the passenger's neck is thrown backward. This is the neck's desire to remain at rest, even when force to move it is being acted upon it. When trying to get ketchup from a bottle, throwing the bottle toward the table, then stopping it suddenly causes the ketchup to come out of the bottle. This occurs because when the ketchup is being thrown toward the table, the ketchup is moving. When the bottle stops, the ketchup will keep moving because of the condiment's desire to keep moving. Even when the action ends, the object keeps moving, because of its desire to keep moving.
 * Newton's 1st law** =Once an object is in motion, it wants to remain in motion. It is an object's nature to maintain its state of motion or rest.

Force is an influence tending to change the motion of the body or produce motion in a stationary body. Force is proportional to mass and acceleration. Net force is the vector sum of all forces acting on an object. Net force is also represented with this equation: netF=//m//a or net force = mass x acceleration. If equal forces are applied to two objects of different masses, the object with greater mass will experience a smaller acceleration and the object with less mass will experience a greater acceleration. The net force is directly proportional to the acceleration of an object. Net force is also inversely inversely proportional to the object's mass. Weight is a measure of the gravitational force exerted on an object. Its value can change with the location of the object in the universe. Mass is the quantity of matter that a body contains as measured by its acceleration under a given force or by the force exerted on it by the gravitational field. Since weight is equal to the magnitude of the force due to gravity, weight depends on location, while mass is constant anywhere. For example, an astronaut weighing 180 pounds on Earth, will only weigh 30 pounds on the moon. The mass remains constant in both places.
 * Newton's 2nd law**

For every action, there is an equal and opposite reaction. Normal force is a force that acts on a surface in a direction perpendicular to the surface. When a car hits a tree, the car exerts force onto the tree, and tree exerts force on the car. Friction is the resistance a surface or object encounters when moving over another. The coeffecient of friction is the ratio of the force of friction to the normal force between two surfaces. The coeffecient of kinetic friction is the force of kinetic friction over the normal force. The coefficient of static friction is the ratio of the maximum value of the force of static friction to the normal force. Friction depends on the composition and qualities of the surfaces in contact. The normal force also affects friction. Kinetic friction is the force that opposes the movement of two surfaces that are in contact and are sliding over each other. Static friction is the force that resists the initiation of sliding motion between two surfaces that are in contact and at rest. Static friction deals with stationary objects, while the kinetic deals with moving objects.
 * Newton's 3rd law**