Today’s Objectives  Understand what a simple machine is and how it can be used.  Learn about a Rube Goldberg Machine. Understand how to construct one using simple machines.  Understand what a simple machine is and how it can be used.  Learn about a Rube Goldberg Machine. Understand how to construct one using simple machines.

What is a simple machine?  A machine should assist you in doing work however, the amount of work done overall is the same  The most basic objects that redirect force are called simple machines  A machine should assist you in doing work however, the amount of work done overall is the same  The most basic objects that redirect force are called simple machines

Example of a Simple Machine Remember: Work = Force x Distance

What is a Complex Machine?  More than 1 simple machine to redirect the work is known as a complex machine.  Also known as a compound machine.  Examples of complex machines:  Scissors, which use two first class levers joined at a common fulcrum  A car jack, which uses a lever in combination with a large screw  More than 1 simple machine to redirect the work is known as a complex machine.  Also known as a compound machine.  Examples of complex machines:  Scissors, which use two first class levers joined at a common fulcrum  A car jack, which uses a lever in combination with a large screw

Why Use Simple Machines? Since… Work = Force x Distance AND overall Work of the system stays constant… If you increase the force, you decrease the distance covered OR If you increase the distance, you decrease the force input by the user

Become an Expert: Inclined Plane What are we learning about?

What is an inclined plane?  Inclined Planes multiply and redirect force  An inclined plane turns a small input force in to a large output force by spreading the work out over more distance  Inclined Planes multiply and redirect force  An inclined plane turns a small input force in to a large output force by spreading the work out over more distance

The Inclined Plane Family  A screw is an inclined plane wrapped around a cylinder  Screws require less force to insert than nails, but you cover more distance because you have to twist it so many times  A screw is an inclined plane wrapped around a cylinder  Screws require less force to insert than nails, but you cover more distance because you have to twist it so many times

The Inclined Plane Family  A wedge is a modified incline plane  Used to change direction of a force  Allows you to apply a force down onto the wedge and redirects to force to the sides  Ex: an ax splitting wood  Note: cheese is not really an example of an inclined plane, unless you use it as a ramp  A wedge is a modified incline plane  Used to change direction of a force  Allows you to apply a force down onto the wedge and redirects to force to the sides  Ex: an ax splitting wood  Note: cheese is not really an example of an inclined plane, unless you use it as a ramp

Become an Expert: Pulley What are we learning about?

Pulleys  The point of rotation on a pulley is the fulcrum and the arm will bend around the fulcrum.

Fixed Pulleys  In a fixed pulley the fulcrum is attached to a base or structure.  The input force direction is opposite the output force direction.  Since you input a downward force on the rope, the output force causes the bucket to move up.  In a fixed pulley the fulcrum is attached to a base or structure.  The input force direction is opposite the output force direction.  Since you input a downward force on the rope, the output force causes the bucket to move up.

Non-Fixed Pulleys o Non-fixed pulleys have the fulcrum NOT attached to a base or structure. o The input force and output force are in relatively the same direction.

Pulleys  Multiple pulleys are sometimes put together in a single unit called a block and tackle

“Real Life” Examples

Become an Expert: Lever What are we learning about?

The Lever Family  Levers have a rigid arm and a fulcrum  Rigid Arm: the body of the lever where the output and input are applied  Fulcrum: the pivot about which a lever turns  Levers are divided into three classes  Levers have a rigid arm and a fulcrum  Rigid Arm: the body of the lever where the output and input are applied  Fulcrum: the pivot about which a lever turns  Levers are divided into three classes Arm Fulcrum

First-Class Levers  All first-class levers have a fulcrum located between the points of application of the input and the output forces  Fulcrum is not necessarily visible or in the exact center  Example: a teeter-totter (see-saw)  All first-class levers have a fulcrum located between the points of application of the input and the output forces  Fulcrum is not necessarily visible or in the exact center  Example: a teeter-totter (see-saw) Arm Fulcrum Input Force Output Force

Second-Class Levers  In a second-class lever, the fulcrum is at one end of the arm and input force is applied to the other end, with the output in between  Example: A wheel barrow  In a second-class lever, the fulcrum is at one end of the arm and input force is applied to the other end, with the output in between  Example: A wheel barrow Arm Fulcrum Input Force Output Force

Third-Class Levers  In third-class levers, the input force is between the output force and the fulcrum  Example: Fishing Rod  In third-class levers, the input force is between the output force and the fulcrum  Example: Fishing Rod Arm Fulcrum Input Force Output Force

Examples of Levers Note: You will not need to be able to differentiate between the 3 classes. 3 rd class 2 nd class 1 st class