Change an object’s motion Do not change an object’s motion Net force = 0 N Push or pull Have direction Net force does not equal 0 N B O T H Balanced Forces Unbalanced Forces

Unbalanced Forces B O T H Balanced Forces Doesn’t change an object’s motion Change an object’s motion Push or pull Have direction Net force = 0 N Net force does not equal 0 N

Newton’s Laws of Motion 9.3 Pgs. 340-347

Take a look at this!! http://www.youtube.com/watch?v=TKQD2Flo9IY

Newton’s First Law of Motion An object at rest will stay at rest unless acted upon by a nonzero net force. An object moving will continue moving unless acted upon by a nonzero net force.

Because of inertia, I resist changes in motion. When the coaster accelerates over a hill, inertia keeps me moving at a constant velocity. I feel tossed around. objects only change motion when a nonzero net force acts on them.

Newton’s First Law video clip

Inertia Resistance to change in motion.

Inertia depends on mass The greater the mass of an object, the greater its inertia, and the greater the force required to change its motion.

Newton’s Second Law of Motion An object’s acceleration depends on its mass and on the net force acting on it. Acceleration = Net force Mass Net force = Mass X Acceleration

More dogs could be added OR passengers could be removed. Dogs could be removed OR passengers could be added.

100 N/50 kg = 2 m/s2 50 kg X 9.8 m/s2 = 490 N

Force = Mass X Acceleration It would be cut in half to Become 1 m/s2 2 kg X 2 m/s2 = 4 N among force, mass, and acceleration.

Newton’s Third Law of Motion If one object exerts a force on another object, then the second object exerts a force of equal strength in the opposite direction on the first object. For every action there is an equal but opposite reaction.

Action-Reaction Pairs examples…

Action-Reaction Pairs

Newton’s Third Law of Motion

for every action force there is an equal and opposite reaction force.