Lesson 1.1 Mechanisms



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|Lesson 1.1 Mechanisms |

Concepts

Engineers and engineering technologists apply math, science, and discipline-specific skills to solve problems.

Engineering and engineering technology careers offer creative job opportunities for individuals with a wide variety of backgrounds and goals.

Technical communication can be accomplished in oral, written, and visual forms and must be organized in a clear and concise manner.

Most mechanisms are composed of gears, sprockets, pulley systems, and simple machines.

Mechanisms are used to redirect energy within a system by manipulating force, speed, and distance.

Mechanical advantage ratios mathematically evaluate input work versus output work of mechanisms.

Performance Objectives

It is expected that students will:

Differentiate between engineering and engineering technology.

Conduct a professional interview and reflect on it in writing.

Identify and differentiate among different engineering disciplines.

Measure forces and distances related to mechanisms.

Distinguish between the six simple machines, their attributes, and components.

Calculate mechanical advantage and drive ratios of mechanisms.

Design, create, and test gear, pulley, and sprocket systems.

Calculate work and power in mechanical systems.

Determine efficiency in a mechanical system.

Design, create, test, and evaluate a compound machine design.

Essential Questions

1. Why is it important to begin considering career paths during high school?

2. What career opportunities are available to match your specific interests?

3. What are some current applications of simple machines, gears, pulleys, and sprockets?

4. What are some strategies that can be used to make everyday mechanisms more efficient?

5. What are the trade-offs of mechanical advantage related to design?

6. Why must efficiency be calculated and understood during the design process?

Key Terms

|ABET |The recognized accreditor for college and university programs in applied science, computing, |

| |engineering, and technology. |

|Actual Mechanical Advantage |The ratio of the magnitude of the resistance and effort forces applied a system. |

|Belt |A continuous band of tough flexible material used to transmit motion and power within a pulley |

| |system. |

|Career |A profession for which one trains and which is undertaken as a permanent calling. |

|Chain |A series of usually metal links or rings connected to or fitted into one another and used to |

| |transmit motion and power within a sprocket system. |

|Effort Force |An external force applied to an object. |

|Efficiency |The ratio of useful energy output to the total energy input, or the percentage of the work input |

| |that is converted to work output. |

|Friction |The resistance that one surface or object encounters when moving over another. |

|Fulcrum |The fixed point around which a lever rotates. |

|Gear |A circular toothed object used to transfer rotary motion and torque through interlocking teeth. |

|Ideal Mechanical Advantage |Ratio of distance traveled by the applied effort and resistance force within a system. |

|Idler Gear |A gear positioned between the driver and the driven gear used to change rotational direction. |

|Inclined Plane |A flat surface set at an angle or an incline with no moving parts that is able to lift objects by |

| |pushing or pulling the load. |

|Lever |A rigid bar used to exert a pressure or sustain a weight at one point of its length by the |

| |application of a force at a second and turning at a third on a fulcrum. |

|Mechanism |The structure of or the relationship of the parts in a machine, or in a construction or process |

| |comparable to a machine. |

|Moment |The turning effect of a force about a point equal to the magnitude of the force times the |

| |perpendicular distance from the point to the line of action from the force. |

|Pitch |Distance between adjacent threads in a screw. |

|Pulley |A type of lever that is a wheel with a groove in its rim, which is used to change the direction or |

| |multiply a force exerted by a rope or cable. |

|Resistance Force |Impeding effect exerted by one material object on another. |

|Screw |An inclined plane wrapped around a cylinder, forming the path and pitch. |

|Simple Machine |Any of various elementary mechanisms including the lever, the wheel and axle, the pulley, the |

| |inclined plane, the wedge, and the screw. |

|Sprocket |A toothed wheel whose teeth engage the links of a chain. |

|Static Equilibrium |A condition where there are no net external forces acting upon a particle or rigid body and the body|

| |remains at rest or continues at a constant velocity. |

|Technical Communication |Creating, designing, and transmitting technical information so that people can understand it easily |

| |and use it safely, effectively, and efficiently. |

|Torque |A force that produces or tends to produce rotation or torsion. |

|Wedge |A substance that tapers to a thin edge and is used for splitting, raising heavy bodies, or for |

| |tightening by being driven into something. |

|Wheel and Axle |Two different sized circular objects that are attached together and turn as one. |

Instructional Resources

Presentations

Engineer’s Notebook

Careers in Engineering and Engineering Technology

Simple Machines – Lever, Wheel and Axle, and Pulley

Simple Machines – Inclined Plane, Wedge, and Screw

Gears, Pulley Drives, and Sprockets

Optional – Fischertechnik® Mechanisms

Word Documents

Sample Engineer’s Notebook Entries

Professional Interview

Activity 1.1.1 Simple Machine Investigation

Activity 1.1.2 Simple Machine Practice Problems

Activity 1.1.3 Gears

Activity 1.1.4 Pulley Drives and Sprockets

Activity 1.1.5 Gears, Pulley Drives, and Sprockets Practice Problems

Project 1.1.6 Compound Machine Design

Understanding Thread Notes

Lesson 1.1 Key Terms Crossword

Reference Sources

ABET. (2008). Retrieved May 13, 2008, from

American Society of Manufacturing Engineers. (2008). Mechanical engineering & mechanical engineering technology: Which path will you take? Retrieved May 28, 2008, from

Aubrecht, J.A. (1995). Energy (2nd ed.). Upper Saddle River, NJ: Prentice Hall.

Brain, M. (2007). How gear ratios work. Retrieved January 8, 2008, from

Gage, M., & Gage, J. (2005). The art of splitting stone: Early rock quarrying methods in pre-industrial New England 1630-1825. Amesbury: Powwow River Books.

Herman, S.L. (2004). Delmar’s standard book of electricity (3rd ed.). United States: Thomson Learning, Inc.

Hewitt, P. G. (2002). Conceptual physics. Upper Saddle River, New Jersey: Prentice Hall.

International Technology Education Association (ITEA). (2000). Standards for technological literacy. Reston, VA: ITEA.

Kubala, T. (2006). Electricity 1: Devices, circuits, and, materials (8th ed.). United States: Thomson Learning, Inc.

Litowitz, L.S. & Brown, R. A. (2007). Energy, power, and transportation technology. Tinley Park, IL: The Goodheart-Wilcox Company, Inc.

Markel, M. (2003). Technical communication (6th ed.). New York, NY: St. Martin’s Press.

Merriam-Webster. (n.d.). Merriam-Webster online. Retrieved December 15, 2007, from

Microsoft, Inc. (n.d.). Clip art. Retrieved January 10, 2008, from

National Council of Teachers of English (NCTE) and International Reading Association (IRA) (1996). Standards for the English language arts. Newark, DE: IRA; Urbana, IL: NCTE.

National Council of Teachers of Mathematics (NCTM). (2000). Principles and standards for school mathematics. Reston, VA: Author.

National Research Council (NRC). (1996). National science education standards. Washington, D. C.: National Academy Press.

Naval Education and Training Program Development Center. (1994). Basic machines and how they work. (Rev. ed.). Mineola, NY: Dover Publications, Inc.

Oxford English Dictionary. (n.d.). OED Online. Retrieved January 18, 2008, from

Oxford University Press. (n.d.). AskOxford: Oxford reference online. Retrieved December 15, 2007, from

Remick, P. & Cook. F. (2007). 21 things every future engineer should know: A practical guide for students and parents. Chicago, IL: Kaplan AEC Education.

Wentzell, T.H. (2004). Machine design. United States: Thomson Learning, Inc.

Wright R.T. (1996). Technology systems. South Holland, IL: The Goodheart-Wilcox Company, Inc.

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