Download Force and Newton`s Laws

Newton’s Laws of Motion
 Forces
 Any push or pull -may change speed or
direction
 Net Force: Total force felt by an object.
 Balanced forces: no change in motion
 Unbalanced forces: acceleration occurs
 Newton’s First law of motion: (Law of
Inertia)
 An object in motion tends to stay in
motion; an object at rest tends to stay at
rest, unless acted on by an outside force.
 “An object will remain at rest or move
with constant velocity until it is acted upon
by a net force.”
 Inertia:
 A resistance to change in motion (a.k.a. Momentum)
 Friction:
 A force caused by two surfaces rubbing together. Usually opposes motion.
 Types:
 Static-resistance to start moving when at rest
 Sliding-friction between a moving object and the surface
 Rolling-takes place at the contact point of a wheel and the surface it is on.
 Fluid-friction: acting on the front of an object moving through either a gas
or liquid.
 Lubricant: A slippery substance used to reduce friction.
 Newton’s Second Law of motion:
 The acceleration of an object of a certain mass is determined by the size of the
force acting and the direction in which it acts.

Accleration 
NetForce
or, Fnet=ma
Mass
 Momentum=Mass X Velocity
 A change in momentum is dependent on the amount of time the force acts on the
object:
 F x t=mv2-mv1
 Normal Force-a force acting at a right angle to the surface.
 Gravity is a normal force
 Terminal Velocity: Greatest speed an object can fall due to air resistance. Forces
are balanced.
 Circular Motion: Constant Acceleration due to Centripetal Force, (Centripetaltoward the center-->a) and a force tangent to the circle (in the direction of v).
 Newton’s Third Law of motion:
 For every action there’s an equal and opposite reaction.
 Law of Conservation of Momentum
 In a closed system, Momentum can be transferred from one object to another, but
cannot change in total amount.