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Totally Trebuchet Overview Introduction The GEARS-EDS Totally Trebuchet Program combines SolidWorks® with STEM based lessons and activities. The comprehensive Totally Trebuchet Program described on these two pages is available from GEARS-EDS at http://www.gearseds.com/ or from SolidWorks resellers. Included on the disk is a small sampling of our math, science and engineering curriculum. Trebuchets are fun to design, build and use.
Totally Trebuchet Educational Components Totally Trebuchet is a complete set of educational tools and text materials designed to provide a comprehensive introduction to science, math and engineering studies (6 to 8 week program). • GEARS-IDS™ Trebuchet Kit and Construction Manual Rugged and re-configurable structural components designed to withstand the yearly demands of classroom service. These materials are organized in a storage container for easy classroom management.
Sample Math Curriculum Pages M1-M4
Sample Math Curriculum Perimeter, Area and Volume Activity Describing and Visualizing Totally Trebuchet Geometry Activity #1 The Axle – Cross Section and Span Sketch the GEARS trebuchet axle and label the dimensions on a separate sheet of paper. Remember to include this sketch and all accompanying calculations and answers in your build report. Throwing arm assembly The trebuchet axle is a critical component; supporting many times its own weight across a span many times its diameter.
Sample Math Curriculum Perimeter, Area and Volume Activity Describing and Visualizing Totally Trebuchet Geometry Activity #2 Investigating SolidWorks - Geometry and Visualization Powerful geometry tools are built into SolidWorks design software. They can be accessed using the TOOLS section in the standard toolbar menu. The tools used in this activity are MEASURE and MASS PROPERTIES. Directions: Practice using the MEASURE and MASS PROPERTIES tools. 1. 2. 3. 4. 5. 6. Open SolidWorks and create a 1Ǝ (25.
Sample Math Curriculum Volume Formulas for Solid Objects Volume = (Length x Height) x Width Volume = (?1 2Length x Height) x Width Length Length Height Width Base Width Height Volume of a Triangular Prism Volume of a Rectangular Prism Volume = ( x Radius2) x Depth Volume = 4/3 x Radius3 Diameter Radius Radius Depth Volume of a Cylinder Volume of a Cylinder Volume = 1/3 (Area Base x Height) Volume = 1/3 x Radius2 x Height Height Height Width Length Radius Volume of a Pyrami
Sample Math Curriculum Assessment Rubric: Perimeter-Area-Volume Describing and Visualizing Totally Trebuchet Geometry This rubric is offered as an example. Teachers and students are encouraged to create assessment tools that reflect their needs and expectations.
Sample Science Curriculum Pages S1-S8
Sample Science Curriculum Lesson 2: Mass, Gravity, Weight and Density Visualizing and Describing The Science of Totally Trebuchet Mass is the measure of the amount of material in an object. It is the nature of all mass to be mutually attractive. This force of attraction is called gravity. Gravity is proportional to mass. Therefore the most significant gravitational force is due to the earth itself.
Sample Science Curriculum Gravity Gravity is a force of attraction that acts between all matter. Gravity is measured by the rate at which it can accelerate mass. SI acceleration is measured in meters per second per second (m/s2). Imperial acceleration is measured in feet per second per second (ft/s2). x Gravity is a fundamental property of all mass. All mass has gravity all mass exerts gravitational forces that attract all other masses. x The force of gravity is a vector quantity.
Sample Science Curriculum Gravity Revisited: A Force to Reckon With (SI Units Only) Mass and weight are used interchangeably in daily life. For practical purposes the force of gravity over the earth’s surface is considered to be constant. (It actually varies with respect to altitude or distance from the earth’s center and local variations in density.) Weight and mass are equivalent expressions when the force of gravity is considered to be constant.
Sample Science Curriculum Density Density is a material property. The density of an object varies as a ratio of mass to volume. Specific materials have specific densities. Density is a measure of the amount of mass contained in a unit of volume. SI Units Imperial Units Example Material Densities Kg/m3 Kg/cm3 g/cm3 g/ml lbs/ft3 lbs/inch3 lbs/yd3 oz/inch3 Aluminum Steel Copper Gold Titanium Polycarbonate 2.7 g/cm3 7.84 g/cm3 8.85 g/cm3 19.32 g/cm3 4.5 g/cm3 1.
Sample Science Curriculum Activity #1: Calculate and Compare Density Visualizing and Describing The Science of Totally Trebuchet In this exercise we will use some of what we know about mass, volume and density to compute and compare the density of the 1-1/2Ǝ (38mm) diameter lead counterweight and wood sphere found in the GEARS Totally Trebuchet Kit. Materials Balance Scale 1-1/2Ǝ (38mm) lead counterweight and wood sphere. Calculator Procedure 1. Record the mass of the spheres.
Sample Science Curriculum Activity #2: Designing Counterweights Visualizing and Describing The Science of Totally Trebuchet Bigger, Stronger and Heavier Ancient trebuchet engineers learned to build trebuchets the hard way, through trial and error. As castle defenses were fortified, trebuchet builders responded by constructing increasingly larger trebuchets. This meant more massive counterweights were needed to overcome the inertia of the bigger beams, and hurl heavier payloads higher and farther.
Sample Science Curriculum Work Sheet Activity #2: Designing Counterweights Visualizing and Describing The Science of Totally Trebuchet Name____________________________ Date________________________ Note: You will need to include and attach additional papers to complete this worksheet. Sketches Create a three-view sketch of the counterweight bucket design you choose to use. Include top, front and right side views.
Sample Science Curriculum Assessment Rubric: Mass, Density, Weight and Gravity Describing and Visualizing the Science of Totally Trebuchet This rubric is offered as an example. Teachers and students are encouraged to create assessment tools that reflect their needs and expectations.
Sample Engineering Curriculum Pages E1-E10
Sample Engineering Curriculum Activity #9: Analyzing the Stress on the Trebuchet Axle Visualizing and Describing the Engineering of Totally Trebuchet Engineers are responsible for designing and building machines, structures, processes, and systems that are dependable, reliable and unlikely to fail when used within the design limitations for which they were engineered. You might consider this the next time you are a passenger on a train, plane or automobile, or as you cross a bridge or ride an elevator.
Sample Engineering Curriculum An Illustrated Look at Forces Acting on the Trebuchet Axle A force that acts perpendicular to the center axis of the trebuchet axle will cause the axle to bend. This is called deflection. The amount of deflection is proportional to the applied force and inversely proportional to the cross sectional area of the axle. This simply means that if the axle is larger in diameter, it will support greater loads and deflect less.
Sample Engineering Curriculum Force, Deflection, Stress and Yield The loads or forces applied to the axle are called stress. Stress is a measure of force per unit area. An example might be pounds per square inch or Newtons per square centimeter. A given amount of stress (Force per unit area) will cause a given amount of change in the shape or length of the axle. This change in length is called strain.
Sample Engineering Curriculum The Trebuchet Axle The trebuchet axle supports forces generated by the rotating counterweight, beam, and projectile. The axle is subject to significant dynamic (due to motion) forces during the throw and static (stationary) loads when it is at rest. These forces and loads act to bend (deflect) the axle. If the axle is not strong enough to support these loads, it will deflect causing permanent deformation of the axle.
Sample Engineering Curriculum Analyzing the Stress on the Trebuchet Axle continued Will a Trebuchet Axle Fail? The bending or breaking of the axle is likely to be the most frequent source of failure in a trebuchet system. In order to prevent axle failure, it is necessary to determine if the axle can support the loads imposed by the standing beam system as well as the more significant loads imposed by throwing. It is possible to determine if the axle can support the loads in several different ways: 1.
Sample Engineering Curriculum Analyzing the Stress on the Trebuchet Axle continued For an axle with a given radius, and material: The greater the force P, and the span L, the more likely it is that the axle will fail. Conversely, if the span L is decreased, the axle will support greater loads. In order to ensure that the axle will not deform (bend) beyond its yield point, it must be designed with an adequate cross section and material strength.
Sample Engineering Curriculum Analyzing the Stress on the Trebuchet Axle continued Follow these steps to use the flexural formula to answer the question “Will it break?” 1. Run the GEARS-TrebStar simulation using the given parameters. 2. Record the value for ( P ), the maximum (Dynamic) load on the axle from the GEARS-TrebStar trebuchet simulator. The maximum dynamic load value, max(Fax/Fcw) =, can be found on the lower right corner of the GEARS-TrebStar interface.
Sample Engineering Curriculum Analyzing the Performance of the Same Axle Using SolidWorks COSMOSXpress SolidWorks offers a handy utility that can be used to quickly determine if and how a trebuchet axle, or other load-bearing component will perform when stressed.
Sample Engineering Curriculum 12. Click Show Me, after the calculations are completed. COSMOSXpress will show a color coded model of the axle. Blue indicates the axle is not being stressed near the material yield point, and that the factor of safety is greater than 1. Red indicates a factor of safety less than 1, or more importantly, that the part will fail under the applied load. 13. After clicking Show Me, click Next, and choose “Show me the stress distribution in the model” radio button.
Sample Engineering Curriculum Engineering Trebuchets Visualizing and Describing The Engineering of Totally Trebuchet This rubric is offered as an example. Teachers and students are encouraged to create assessment tools that reflect their needs and expectations.
