Simple MachinesSimple Machines

Do now: Clear your desk except Do now: Clear your desk except for ISN and pencil. for ISN and pencil.

BE READY to take a few notes.BE READY to take a few notes.

Simple machine-Simple machine- a device a device that does work with only one that does work with only one movement.movement.

-Machines make work easier by -Machines make work easier by changing the force you exert in changing the force you exert in size, direction or both.size, direction or both.

-Simple machines try to move -Simple machines try to move something that resists being something that resists being moved. (Ex: friction or gravity)moved. (Ex: friction or gravity)

Make work easier to do by:

• Increasing the size of an applied force• Changing the direction of an applied force• Changing the distance over which a force acts

There will always be a trade-off!!!

There are 6 types of simple There are 6 types of simple machines. All are variations machines. All are variations of lever or inclined plane.of lever or inclined plane.

LeverLever Inclined planeInclined plane

1. Lever1. Lever 4. Inclined plane4. Inclined plane

2. Pulley2. Pulley 5. Screw5. Screw

3. Wheel and3. Wheel and 6. Wedge6. Wedge

axleaxle

http://cnx.org/content/m23853/latest/ http://www.the-office.com/summerlift/pulleybasics.htm

http://www.g9toengineering.com/resources/simplemachines.htm

http://en.wikipedia.org/wiki/Ferris_wheel http://makeitgo.wikispaces.com/wedges

http://www.schnauzerlover.com/ramp.htm

What goes in…

Input is also called “effort:”-Effort force is the force applied to a machine-Effort distance is the distance across which the effort is applied

What comes out…

http://tech.texasdi.org/simplemachines http://elimeirkaplan.com/blog/?p=608

Output is also called “resistance:”-Resistance force is the force exerted by a machine-Resistance distance is the distance across which the machine applies effort

1.1. Lever- a bar that is free to Lever- a bar that is free to pivot or turn about a fixed pivot or turn about a fixed point.point.

- Fulcrum- fixed point of a lever- Fulcrum- fixed point of a lever- Effort arm- part of the lever Effort arm- part of the lever

where the effort force is where the effort force is appliedapplied

- Resistance arm- part of the Resistance arm- part of the lever where there is resistancelever where there is resistance

FULCRUM

LOAD

EFFORT

Fixed point about whichthe lever rotates

The mass beinglifted by a lever

Force used tolift the load

Review: Force is a push or a pull on an object, and is measured in Newtons

There are different types of There are different types of levers.levers.

-1-1stst class Effort class Effort ▲▲ResistResist

Ex: seesawEx: seesaw

scissorsscissors

plierspliers

-2-2ndnd class class Effort Resist ▲ Effort Resist ▲

Ex: Stapler Ex: Stapler

WheelbarrowWheelbarrow

Nail clippersNail clippers

-3-3rdrd class class ResistResist Effort Effort ▲▲

Ex: Ex: TweezersTweezers

Swinging a batSwinging a bat

Fishing rodFishing rod

2. Pulley- a grooved wheel 2. Pulley- a grooved wheel with rope running along the with rope running along the groove.groove.

There are 3 types of pulleysThere are 3 types of pulleys

1.1. Fixed- the pulley is stationaryFixed- the pulley is stationary

2.2. Movable- the pulley can moveMovable- the pulley can move

3.3. Block and tackle- Fixed and Block and tackle- Fixed and movable put togethermovable put together

-Fixed -Movable -Block &

Pulley Pulley Tackle Pulley

3. 3. Wheel and axle- 2 wheels of Wheel and axle- 2 wheels of different sizes that rotate different sizes that rotate together.together.

- Always travel in a circle.Always travel in a circle.

- Effort force is applied to the Effort force is applied to the larger wheel while the smaller larger wheel while the smaller wheel (axle) exerts the wheel (axle) exerts the resistance force.resistance force.

Example of a wheel and axleExample of a wheel and axle

Wheel and AxleWheel and Axle

A simple machine that is a wheel attached to a A simple machine that is a wheel attached to a shaft, or axle. shaft, or axle.

4. 4. Inclined plane- a sloping Inclined plane- a sloping surface used to raise surface used to raise objectsobjects..

Ex: a ramp. Using a ramp, you Ex: a ramp. Using a ramp, you cover more distance but exerts cover more distance but exerts less force.less force.

Inclined PlaneInclined Plane

A simple machine that is a sloping surface, A simple machine that is a sloping surface, such as a ramp. such as a ramp.

5.5. Screw- an inclined plane Screw- an inclined plane wrapped in a spiral.wrapped in a spiral.

6.6. Wedge- an inclined plane Wedge- an inclined plane with 1 or 2 sloping sides.with 1 or 2 sloping sides.

-Wedges are moving inclined -Wedges are moving inclined planes.planes.

Ex: Knife or ax blade.Ex: Knife or ax blade.

WedgeWedge

A simple machine that has a thick end and a A simple machine that has a thick end and a thin end. A wedge is used to cut, split, or thin end. A wedge is used to cut, split, or pierce objects or to hold objects together. pierce objects or to hold objects together.

Amanda uses a wheelbarrow to lift a load of bricks. The bricks weigh 600 N, which is more than Amanda could normally carry. However, with the wheelbarrow, Amanda can lift the bricks with as little as 120 N. What is the mechanical advantage of the wheelbarrow?

Marshall wants to remove a tree stump from the ground. To do this, he puts one end of a long beam under the stump and puts all of his weight on the other end. His weight is just enough to lift the stump. The stump weighs 400 N. Marshall weighs 250 N. What is the mechanical advantage of the lever Marshall is using?

A 5-meter ramp lifts objects to a height of 0.75 meters. What is the mechanical advantage of the ramp?