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23 Cards in this Set
- Front
- Back
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WORK FORMULA
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WORK = FORCE X DISTANCE
w = f x d w = (m x a) x d |
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TWO CATEGORIES OF WORK
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1. WORK DONE AGAINST ANOTHER FORCE.
2. WORK DONE TO CHANGE THE SPEED OF AN OBJECT. |
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WORK UNITS
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UNIT OF FORCE (N)
xUNIT OF DISTANCE (m) (N x m) = JOULES (J) |
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POWER FORMULA
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WORK DONE/TIME INTERVAL
POWER = (m x a) x d ------------- TIME |
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ENERGY
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ENABLES AN OBJECT TO DO WORK
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MECHANICAL ENERGY
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-ENERGY DUE TO THE POSITION OR MOVEMENT OF AN OBJECT
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FORMS OF MECHANICAL ENERGY
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-POTENTIAL ENERGY (PE)
-KINETIC ENERGY (KE) -SUM OF THE TWO |
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POTENTIAL ENERGY
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-ENERGY THAT IS STORED AND HELD IN READINESS
-HAS POTENTIAL FOR DOING WORK -EX.=BOW IS DRAWN, ENERGY IS STORED IN THE BOW |
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GRAVITATIONAL POTENTIAL ENERGY (GPE)
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-PE DUE TO ELEVATED POSITIONS
-EX.=HAMMER UP IN PILE DRIVER |
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GPE FORMULA
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WEIGHT x HEIGHT
PE = (m x g) x h PE = mgh |
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KINETIC ENERGY (KE)
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-ENERGY OF MOTION
-DEPENDS ON OBJECT MASS AND SPEED |
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KE FORMULA
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KE = ½ mass x speed²
KE = ½mv² |
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KE OF MOVING OBJECT FORMULA
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-NET FORCE x DISTANCE = KE
-Fd = ½ mv² |
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TRANSFER OF KE
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-KE OF MOVING OBJECT IS EQUAL TO THE WORK REQUIRED TO BRING IT FROM REST TO THAT SPEED.
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WORK/ENERGY THEREOM
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-NET WORK = ∆KE
-WORK IS NOT A FORM OF ENERGY, IT IS A WAY OF TRANSFERRING ENERGY FROM ONE PLACE/FORM TO ANOTHER. |
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LAW OF CONSERVATION OF ENERGY
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ENERGY CANNOT BE CREATED OR DESTROYED, IT MAY BE TRANSFORMED FROM ONE FORM INTO ANOTHER, BUT THE TOTAL AMOUNT OF ENERGY NEVER CHANGES.
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MACHINE
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MULTIPLIES OR CHANGES THE DIRECTION OF FORCES
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MACHINE PRINICPLES
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(ideal machine/no heat energy lost)
-WORK(input)=WORK(output) -(Fxd)input = (fxD)output -input FORCE THROUGH A LARGE DISTANCE HEAVY LOAD IS MOVED A SHORT DISTANCE/VICE VERSA |
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EFFICIENCY
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ENERGY OUTPUT OF MACHINE AFTER THERMAL ENERGY IS LOST
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EFFICIENCY FORMULA
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Eff =
USEFUL ENERGY OUTPUT ----------------------------- TOTAL ENERGY INPUT |
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CONSERVATION OF MACHINE ENERGY
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THE WORK OUTPUT OF ANY MACHINE CANNOT EXCEED THE WORK INPUT.
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KE/p COMPARISON
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KE -SCALAR QUANTITY
-TOTAL KE OF 2 MOVING OBJECTS > EITHER OBJECT ALONE -DIRECTLY PROPORTIONAL TO SQUARE OF VELOCITY (½mv²) p -VECTOR QUANTITY -TWO p'S MAY PARTIALLY OR FULLY CANCEL. -PROPORTIONAL TO VELOCITY (mv) |
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WORK DEFINITION
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-WORK EQUALS CHANGE IN KINETIC ENERGY
w = ∆ KE |
