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23 Cards in this Set

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WORK FORMULA
WORK = FORCE X DISTANCE

w = f x d

w = (m x a) x d
TWO CATEGORIES OF WORK
1. WORK DONE AGAINST ANOTHER FORCE.

2. WORK DONE TO CHANGE THE SPEED OF AN OBJECT.
WORK UNITS
UNIT OF FORCE (N)
xUNIT OF DISTANCE (m)

(N x m) = JOULES (J)
POWER FORMULA
WORK DONE/TIME INTERVAL

POWER =

(m x a) x d
-------------
TIME
ENERGY
ENABLES AN OBJECT TO DO WORK
MECHANICAL ENERGY
-ENERGY DUE TO THE POSITION OR MOVEMENT OF AN OBJECT
FORMS OF MECHANICAL ENERGY
-POTENTIAL ENERGY (PE)
-KINETIC ENERGY (KE)
-SUM OF THE TWO
POTENTIAL ENERGY
-ENERGY THAT IS STORED AND HELD IN READINESS
-HAS POTENTIAL FOR DOING WORK
-EX.=BOW IS DRAWN, ENERGY IS STORED IN THE BOW
GRAVITATIONAL POTENTIAL ENERGY (GPE)
-PE DUE TO ELEVATED POSITIONS
-EX.=HAMMER UP IN PILE DRIVER
GPE FORMULA
WEIGHT x HEIGHT

PE = (m x g) x h

PE = mgh
KINETIC ENERGY (KE)
-ENERGY OF MOTION
-DEPENDS ON OBJECT MASS AND SPEED
KE FORMULA
KE = ½ mass x speed²

KE = ½mv²
KE OF MOVING OBJECT FORMULA
-NET FORCE x DISTANCE = KE

-Fd = ½ mv²
TRANSFER OF KE
-KE OF MOVING OBJECT IS EQUAL TO THE WORK REQUIRED TO BRING IT FROM REST TO THAT SPEED.
WORK/ENERGY THEREOM
-NET WORK = ∆KE

-WORK IS NOT A FORM OF ENERGY, IT IS A WAY OF TRANSFERRING ENERGY FROM ONE PLACE/FORM TO ANOTHER.
LAW OF CONSERVATION OF ENERGY
ENERGY CANNOT BE CREATED OR DESTROYED, IT MAY BE TRANSFORMED FROM ONE FORM INTO ANOTHER, BUT THE TOTAL AMOUNT OF ENERGY NEVER CHANGES.
MACHINE
MULTIPLIES OR CHANGES THE DIRECTION OF FORCES
MACHINE PRINICPLES
(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
EFFICIENCY
ENERGY OUTPUT OF MACHINE AFTER THERMAL ENERGY IS LOST
EFFICIENCY FORMULA
Eff =

USEFUL ENERGY OUTPUT
-----------------------------
TOTAL ENERGY INPUT
CONSERVATION OF MACHINE ENERGY
THE WORK OUTPUT OF ANY MACHINE CANNOT EXCEED THE WORK INPUT.
KE/p COMPARISON
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)
WORK DEFINITION
-WORK EQUALS CHANGE IN KINETIC ENERGY

w = ∆ KE