Simple Machines
Simple Machines! Simple Machine-a device that makes work easier Six types- inclined plane, wedge, screw, lever, wheel and axle, pulley All simple machines transfer force. Direction and/or magnitude Even though simple machines use less force to move an object, it will be over a greater distance. OR Simple machines can allow you to move further faster but with more force.\ Mechanical Advantage Formula: MA=Force Out/Force Inn
Simple Machines Inclined Plane- a flat surface that slopes Ex. ramp Only simple machine that does not move Trade-Off for less force is greater distance. This is how Egyptian Pyramids were made!
Simple Machines Wedge- an inclined plane that moves Used to split or lift objects It takes less force to drive into or under an object than it does to separate or lift the object yourself. Two inclined planes put together The closer the angle of the plane the sharper the object. Examples: knife, fork, nail points, plows, axes, scissor blades and saws
Simple Machines Screw- an inclined plane wrapped around a cylinder Thread- spiral ridges outside of the cylinder As the screw is turned the thread pull the object up the shaft. It takes less force to turn a screw than to pound a nail the same size. The more threads there are on the screw the longer the incline so the easier it is to turn.
Simple Machines Lever- long rigid bar that rests on and pivots around a fulcrum Fulcrum-support for a lever Effort-force applied to the lever Load- force at the part of the lever which needs to be moved There are 3 types of levers: First-class, Second-class and Third-class.
Lever First-class- Fulcrum is near the center with the force and load at opposite ends Examples-scissors, seesaw, pliers
Lever Second-class-The load is in the center with the effort and the fulcrum on opposite ends. Examples- nut crackers, wheel barrow
Lever Third-class-effort in the center with fulcrum and load on opposite ends Example catapult, human arm, hoe
Simple Machines Wheel and Axle- consists of a shaft (axle) inserted through the middle of a wheel. The difference between the size between the wheel and the axle caused the force to get magnified. Examples, bicycles, ferris wheels, steering wheel, door knobs, wrenches
Simple Machines Pulley-a wheel with a rope (or chain) wrapped around it The wheel rotates on a fixed axle. When the rope is pulled the wheel turns Two types of pulleys: fixed, movable.
Pulley Fixed pulley- one end is tied to an object so that pulley does not move
Pulley Moveable Pulley-has a free axle and is used to redirect the force.
Pulley Block and tackle- a system of pulleys Using more than one pulley reduces the amount of force needed to lift the load.