simple machines in your world!
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Simple Machines in your world!. Imagine… eating soup without a spoon hauling dirt without a wheelbarrow opening a door without a doorknob …That is what life would be like without simple machines. Machines are not limited to the complicated devices such as cars, computers, and airplanes!. - PowerPoint PPT PresentationTRANSCRIPT
Simple Machines in your world!
Imagine…• eating soup without a spoon• hauling dirt without a wheelbarrow• opening a door without a doorknob
…That is what life would be like without simple machines.
Machines are not limited to the complicated devices such as cars, computers,
and airplanes!• A machine is any
device that makes work easier.
• They make work easier by placing forces where we want them, by moving things faster, and by making forces larger.
Friction Review
FrictionFriction is the force we feel when is the force we feel when things rub against each otherthings rub against each other
The more things are pushed The more things are pushed together, the more friction there istogether, the more friction there is
It is the force that It is the force that opposesopposes motion motion..
Friction ReviewFriction slows down the movement of Friction slows down the movement of
things and turns motion into thermal things and turns motion into thermal energy (heat).energy (heat).
When you When you rub your hands togetherrub your hands together you can feel the thermal energy you can feel the thermal energy produced.produced.
The mucus from The mucus from aa slugslug will will decreasedecrease friction as the slug slides along the friction as the slug slides along the ground.ground.
Simple MachinesSimple Machines
The purpose of a simple machine is to
A. increase the speed of workB. change direction the force is acting inC. increase Mechanical Advantage
- a machine’s ability to multiply input force
Presenting the 6 simple machines:1. LEVER
2. INCLINED PLANE3. WEDGE4. SCREW
5. WHEEL AND AXLE6. PULLEY
Inclined Plane:
• A simple machine with no moving parts.
• It increases the distance the object moves, but it decreases the amount
of force needed to move it.• It is simply a straight slanted
surface.• An example - a ramp, roadways, slide, roadways, slide,
stairsstairs
Wedge:• An inclined plane
that moves.• Most are made of
TWO inclined planes.• Examples:
– ax– knife– and zippers!
Screw:• An inclined plane wrapped around a
central bar to form a spiral.• A screw increases the distance which
decreases the force needed.• Examples:
– Screws– Jar lids
Lever:• An arm that “pivots” (or turns)
around a fixed point• The fixed point is called the
fulcrum.• A lever increases the distance
to decrease the force required.• Examples:
– seesaw– wheelbarrow– fishing pole
Wheel and Axle:• A simple machine made up of 2
circular objects of different sizes.• The wheel is the larger object and
turns about the small object, (the axle).
• Because the wheel is larger than the axle, it moves a greater distance.
• Examples:– roller skates– doorknobs
Pulley:• A rope, belt, or chain
wrapped around a grooved wheel
• Works in 2 ways:– changes the direction of the
force• or
– changes the amount of force
• Examples:– flagpole– sails on a sailboat
So What??????• Like you heard at the beginning, machines make
work easier. The measure of how much easier is called the mechanical advantage.
• It is important to note that the work that comes out of a machine is never greater than the work put into a machine. In fact, machines actually require more energy to do the same job, even though they make the job easier!
• Most of the machines we use today are compound machines - two or more simple machines working together!