ENERGY

KINETIC ENERGY ENERGY OF MOTION THE FASTER AN OBJECT MOVES; THE MORE KE IT WILL HAVE KE IS ALWAYS “+”, IF YOU ARE MOVING; THEN YOU HAVE IT. EXAMPLE: A 1200KG CAR TRAVELING AT 15M/S (35MPH) HAS WHAT KE? IF THE CAR NOW TRAVELS AT 30M/S (70MPH), WHAT KE DOES IT HAVE? HOW MUCH DID THE KE CHANGE BY WHEN THE CAR DOUBLED ITS SPEED

GRAVITATIONAL POTENTIAL ENERGY mg h Since this man is lifting the package upward at a CONSTANT SPEED, the kinetic energy is NOT CHANGING. Therefore the work that he does goes into what is called the ENERGY OF POSITION or POTENTIAL ENERGY. All potential energy is considering to be energy that is STORED!

IMPORTANT POINTS USE THE MAGNITUDE ONLY FOR “ ” THE HEIGHT ( ) IS MEASURED FROM A REFERENCE LINE THAT WE CALL THE “ZERO LEVEL”. THIS IS USUALLY THE GROUND BUT CAN BE ANYWHERE. IS “+” IF YOU MEASURE ABOVE THE ZERO LEVEL IS “-” IF YOU MEASURE BELOW THE ZERO LEVEL. EXAMPLE: g h h h

POTENTIAL ENERGY h The man shown lifts a 10 kg package 2 meters above the ground. What is the potential energy given to the package by the man? 196 J

ELASTIC POTENTIAL ENERGY ENERGY ASSOCIATED WHEN AN OBJECT IS STRETCHED OR COMPRESSED THIS ENERGY WANTS TO “RESTORE” THE OBJECT BACK TO ITS ORIGINAL SHAPE DEPENDS ON HOW FAR YOU DISTORT THE OBJECT AND ITS SPRING CONSTANT THE SPRING CONSTANT TELLS YOU HOW EASY OR HARD IT IS TO DISTORT THE OBJECT. HIGHER SPRING CONSTANT = THE MORE RIGID THE OBJECT IS K = THE SPRING CONSTANT (UNITS: N/M) X = THE DISTANCE THE SPRING IS STRETCHED OR COMPRESSED FROM ITS RELAXED POSITION EXAMPLES SPRINGS RUBBER BANDS BUNGEE CORDS BASKETBALL, TENNIS BALL, GOLF BALL, ETC.

CONVERTING ME MECHANICAL ENERGY AN OBJECT CAN HAVE ANY COMBINATION OF THESE ENERGIES AT ONE TIME OR NONE AT ALL. EX. A BALL AT REST ON THE FLOOR NONE ALL BALL FALLING TO THE GROUND GPE AND KE A BALL AT ITS HIGHEST POINT. GPE A BALL HITTING THE GROUND EPE ME CAN BE CONVERTED TO OTHER FORMS: A ROLLER COASTER RIDE A BALL FALLING TO THE GROUND A BUNGEE JUMP

DEMOS COLORED TRACK PENDULUM ENERGY RAMP