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NOW THE WEIGHTS ARE BEING GENTLY
LOWERED TO THE GROUND
YOU ARE PUSHING ON THE
CAR, BUT IT IS NOT MOVING
YOU ARE PUSHING THE
CAR UPHILL, BUT IT IS
MOVING DOWNHILL
You are pushing the car
uphill, but it is
moving downhill
YOU CARRY A 1
GALLON JUG OF
MILK ACROSS
THE ROOM.
YOU DRAG A 5
GALLON JUG OF
WATER ACROSS
THE ROOM.
YOU PULL A WAGON DOWN THE
SIDEWALK.
YOU SIT IN THE WAGON AS IT
ROLLS DOWN THE SIDEWALK
You are
holding a
heavy
case of
paper.
You are
running as
fast as you
can down
the track.
You are sitting at your
desk for 2 hours
memorizing a hard poem for class.
Definition of work:A force applied to an object in the same direction that the object moves to
cover some distance.
Lowering weights down is not work because though you are exerting a
force(F) it is in the opposite direction of the movement (d)
W = F • d
W is Work. It is measured in Joules (metric) Foot-pounds (english)
F is force or weight. It can be measured in Newtons or Pounds
d is the distance an object moves that is being acted upon.
A POWER LIFTER RAISING THE WEIGHTS UP INTO
THE AIR
Weight = 315 lbs.
Distance weight was
moved = Volunteer
Work = ???
Is work being done?
THE SAME POWER LIFTER HOLDING
THE WEIGHTS UP
NOW THE 150LB WEIGHTS ARE BEING
GENTLY LOWERED 45 INCHES TO THE
GROUND
YOU ARE PUSHING ON THE
CAR, BUT IT IS NOT MOVING
YOU ARE PUSHING THE
CAR UPHILL, BUT IT IS
MOVING DOWNHILL
You are pushing the car
uphill, but it is
moving downhill
You are
holding a
heavy
case of
paper.
YOU CARRY A 1
GALLON JUG OF
MILK ACROSS
THE ROOM.
YOU DRAG A 5
GALLON JUG OF
WATER ACROSS
THE ROOM.
YOU PULL A WAGON DOWN THE
SIDEWALK.
YOU SIT IN THE WAGON AS IT
ROLLS DOWN THE SIDEWALK
You are
running as
fast as you
can down
the track.
You are
sitting at your
desk for 2
hours
memorizing a
hard poem
for class.
WE CAN MAKE WORK EASIER TO DO BY USING
“SIMPLE MACHINES”
There are 6 simple machines
1. LEVER: TRANSMIT FORCE THROUGH A RIGID
BAR, WHICH PIVOTS ON AN AXIS.
2. WHEEL & AXLE: TAKING A LEVER AND MOVING IT IN A
COMPLETE CIRCLE. THE AXLE MUST MOVE WITH THE
WHEEL AS IT TURNS. IF NOT, IT’S CALLED A PULLEY.
3. PULLEY: A SIMPLE MACHINE THAT CHANGES DIRECTION
OF LINEAR FORCE, BY USING A WHEEL THAT SPINS ON AN
AXLE OR HUB.
4. INCLINED PLANE, RAMPS: A SLOPED SURFACE THAT
ALLOWS OBJECTS TO BE TRANSPORTED VERTICALLY
WITHOUT DIRECTLY LIFTING THEM.
5. WEDGE: A SIMPLE MACHINE WITH A LARGE END
TAPERING TO A THIN EDGE USED FOR SEPARATING
OBJECTS OR SECURING THEM.
6. SCREW: A WEDGE OR INCLINED PLANE THAT
MOVES AROUND A PIVOT POINT
•NUMBER AND NAME EACH OBJECT
•LIST THE SIMPLE MACHINES IN THE OBJECT IF ANY OR
LIST WAYS YOU CAN MAKE IT WORK LIKE A SIMPLE
MACHINE IF IT ISN’T ONE
Simple Machines I.D. Activity
(1 minute per station to identify)
