 We sometimes call this RELATIVE motion.  We have to see something move in relation to something else – we need a FRAME OF REFERENCE

 It’s like a tug-o- war  When both sides are evenly matched, neither one wins, and there is no mevement

 If one side starts to overcome the other, the center of the rope moves toward the stronger side  We have created motion with unbalanced force

Law #1  Objects that are in motion will stay in motion  Objects at rest will stay at rest  Unless a force acts on them

Law #2  For Every Action, there is an equal and opposite reaction  “You push on the floor as hard as the floor pushes back on you.”

Law #3  Force = Mass x acceleration  The bigger you are, the harder you hit  The faster you run, the harder you hit

 Acceleration is an increase or decrease in speed.  Sometimes we say that acceleration is a change in speed.

 No, it’s not Lightning McQueen  Speed is how far you went divided by how look it took to get there  Speed = distance/time

 Gravity accelerates things toward the center of the earth

 The higher above the ground something is, the longer it has to fall, and the faster it will be going when it hits the ground.

 When something is way up high, it has the POTENTIAL to fall a long distance, and get going really fast, so we say it has POTENTIAL ENERGY

 When something finally does fall off, we say that it has KINETIC ENERGY, or the energy of MOTION.

 Remember those unbalanced forces?  When the force of friction slowing down a skiier is not equal to the force of gravity accelerating him, motion happens!

 Friction always acts in the direction opposite of motion.  When there is little friction, funny things happen