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Motion and Energy. Motion is in the eye of the beholder. We sometimes call this RELATIVE motion. We have to see something move in relation to something else – we need a FRAME OF REFERENCE. UNBALANCED forces create motion. It’s like a tug-o-war - PowerPoint PPT Presentation
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MOTION AND ENERGY
MOTION IS IN THE EYE OF THE BEHOLDER
We sometimes call this RELATIVE motion.
We have to see something move in relation to something else – we need a FRAME OF REFERENCE
UNBALANCED FORCES CREATE MOTION
It’s like a tug-o-war
When both sides are evenly matched, neither one wins, and there is no mevement
UNBALANCED FORCES CREATE MOTION
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
ISAAC NEWTON DESCRIBED MOTION IN 3 BRILLIANT “LAWS”
Law #1
Objects that are in motion will stay in motion
Objects at rest will stay at rest
Unless a force acts on them
ISAAC NEWTON DESCRIBED MOTION IN 3 BRILLIANT “LAWS”
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.”
ISAAC NEWTON DESCRIBED MOTION IN 3 BRILLIANT “LAWS”
Law #3
Force = Mass x acceleration
The bigger you are, the harder you hit
The faster you run, the harder you hit
SPEAKING OF ACCELERATION… Acceleration is
an increase or decrease in speed.
Sometimes we say that acceleration is a change in speed.
SO WHAT IS 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
SO WHAT DOES SPEED HAVE TO DO WITH ENERGY AND GRAVITY AND ALL THAT STUFF WE’VE BEEN LEARNING?
Gravity accelerates things toward the center of the earth
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.
GRAVITY ACCELERATES THINGS TOWARD THE CENTER OF THE EARTH
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
GRAVITY ACCELERATES THINGS TOWARD THE CENTER OF THE EARTH When something
finally does fall off, we say that it has KINETIC ENERGY, or the energy of MOTION.
NOW WE’VE COME FULL CIRCLE TO MOTION AGAIN
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!
WHAT WAS THAT ABOUT FRICTION?
Friction always acts in the direction opposite of motion.
When there is little friction, funny things happen