Newton s First Law force Objects tend to keep doing what they were doing unless acted upon by an unbalanced If at rest they remain at rest If in motion they remain in motion The first law of motion only applies when all forces are balanced Balanced motion ex Coffee in a car will remain at rest and stays in the same position Unbalanced motion ex The road pushes on the spinning wheels to accelerate the car forward When the car brakes there is no unbalanced force to change your state of motion making you continue to move forwards Inertia and Mass An object s tendency to resist change in motion is described as inertia The resistance an object has to a change in state of motion Galileo developed this concept He did so by reasoning that moving objects eventually stop because of friction Through inclined plane and ball experiments he concluded that differences between initial and final heights were due to friction Regardless of the angle at which the planes were oriented the final height was almost always equal to the initial height Newton s first law declares that a force is not necessary to keep an object in motion Instead the presence of force is what brings the object to rest An object s inertia is dependent upon its mass The more mass the objects has the more inertia it obtains as well State of Motion An object s state of motion is defined by its velocity Velocity is speed with direction This means that inertia can be the tendency of an object to resist changes in velocity At rest an object has 0 m s velocity An object in motion with a velocity of 2 m s East will remain at 2 m s East until acted upon by an unbalanced force When an object does not change its velocity it has an acceleration of 0 ms s s Balanced and Unbalanced Forces its state of motion An equilibrium is when there is no unbalanced force acting and thus the object maintains Unbalanced forces like friction and gravity change an object s current state of motion Unbalanced forces result in acceleration If two individual forces have equal magnitudes and opposite directions then the forces are said to be balanced An object is considered unbalanced when there is not a balancing force of equal magnitude and opposite direction present Newton s Third Law A force is a push or pull that acts upon an object after it interacts with another object These object exert forces on each other Newton s third law states that for every action there is an equal and opposite reaction This means that there is always a pair of forces acting upon the two interacting objects This is called action reaction pairs Identifying Action and Reaction Force Pairs Action Reaction force pairs are found by identifying the interacting objects and seeing what pushes upon what