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