New Simple Machines

Introduction to Engineering Design

  • Project Lead The Way (PLTW): An educational initiative to enhance student understanding of engineering concepts through practical application.

  • Focus: Simple machines.

The Role of Machines in Work and Engineering

  • Purpose of Machines: Designed to simplify tasks in everyday life.

  • Work: Defined as the measure of force applied to an object over the distance it moves.

  • Functionality of Machines: Machines do not change the total work done; they can modify the force's magnitude and direction.

Effort and Resistance Forces

  • Effort Force: The force you apply when performing work.

  • Resistance Force: The weight of the object or opposing force against your effort.

  • Ways to Simplify Tasks:

    • Reduce the effort force (e.g., push, pull, twist).

    • Shorten the distance of applied effort.

    • Alter the direction of the effort force.

Simple Machines

  • Types of Simple Machines:

    • Wheel and Axle

    • Pulley

    • Lever

    • Inclined Plane

    • Wedge

    • Screw

  • Function: Simple machines manipulate the magnitude of force and distance and can be combined to create compound machines.

  • Energy Principle: Machines do not create energy; they transfer or transform it.

Work

  • Definition of Work (W): Energy transferred when a force (F) is applied to an object moving over a distance (d).

  • Mechanical Work: The product of force magnitude in the direction of movement and the distance moved.

  • Implied Meaning: Work indicates that a force is applied and results in movement.

Mechanical Advantage (MA)

  • Concept of Mechanical Advantage: The MA explains how much a machine amplifies the effort force while performing work.

  • Formulas: Different formulas exist to calculate MA for each type of simple machine.

  • Types of MA:

    • Ideal Mechanical Advantage (IMA): Assumes no energy losses.

    • Actual Mechanical Advantage (AMA): Takes energy losses into account.

Calculating Mechanical Advantage

  • MA Calculation: Can be determined using specific formulas.

  • Example: If MA = 3, and effort force = 10 pounds, it can lift a resistance force = 30 pounds.

  • Importance: MA is a measure of how much a machine changes force magnitude, where greater MA implies less effort required to lift loads.

Wheel and Axle

  • Definition: Composed of two connected circular objects with different diameters.

Special Wheel and Axle

  • Gears: A wheel with teeth that engages with another gear's teeth to change force direction and magnitude.

Pulley

  • Definition: A wheel with a rope running over it, altering the direction of applied force.

  • Combining Pulleys: Multiple pulleys can significantly reduce the effort required to lift objects.

Lever

  • Definition: A bar that pivots around a fixed point (fulcrum).

  • Components of a Lever:

    • Resistance Force

    • Effort Force

    • Fulcrum

Types of Levers

  • First Class: Fulcrum between effort and resistance forces (Effort and Resistance in same direction).

  • Second Class: Resistance force is located between the fulcrum and effort force (Effort and Resistance in opposing direction).

  • Third Class: Effort force is situated between the fulcrum and resistance force (Effort and Resistance in opposing direction).

Inclined Plane

  • Definition: A slanted surface designed to raise an object more easily.

    • IMA Formula: IMA = Length/Height.

Specialized Inclined Planes

  • Wedge: An inclined plan that moves, characterized by a sharp point and used to split or cut.

  • Screw: An inclined plane twisted around a shaft, useful for fastening or moving items.

References

  • Clip art from Microsoft, Inc. (2008). Retrieved from http://office.microsoft.com/en-us/clipart/default.aspx

  • Information sourced from Wikipedia and iStockphoto.