June 22, 2003
June 22, 2003
June 25, 2003
8.3.1 - 8.3.13
“Show Me the Money!” Using Physical Models to Excite Student Interest in Mechanics
Reid Vander Schaaf and J. Ledlie Klosky United States Military Academy
Introduction Students often have difficulty grasping the reality of what is being discussed in introductory courses in mechanics. For some students, especially those who are struggling, physical reality becomes mired in seemingly endless equations and the apparent mish-mash of theory and practical application. This should be prevented if at all possible, as mechanics is the first course in which students can participate in designs that include material type and geometry in a realistic way. One essential method for convincing students of the importance and truth of what you are teaching is to actually show them that truth up close. Students crave reality when confronting engineering topics for the first time. In a sense, students say “Show me the money!”, or “Don’t TELL me, SHOW me…”.
This paper presents a number of simple, low-cost and rapid classroom demonstrations that enhance student understanding by allowing for the direct observation of physical phenomenon. Each of these demonstrations has been thoroughly classroom-tested, and comments on the use of each demonstration are presented. Demonstrations of stress transformation, shear stress, pressure, and load visualization are presented and practical advice on the use and misuse of classroom demonstrations is offered. Student feedback is also presented, and consistently points to the effectiveness of hands-on demonstrations in driving home key points in mechanics.
Conversion of Force and Stress Objective: To clearly show the relationship between force, area and stress, while simultaneously demonstrating a key mechanical concept; the pressurized cylinder and piston system.
Equipment: The equipment required for this demonstration is shown in Figure 1. While somewhat more costly and complex than the other systems presented in this paper, the total cost for materials is still less than $250. Some machining is also required. The device consists of a 3 ft acrylic tube having an inside diameter of 3 in, capped at each end with a threaded PVC cap. The top cap has a hole for the pushrod, and the bottom cap has an access port to which a 15 psi pressure gage and bleeder valve is attached. Additionally, the top of the half-inch pushrod is fitted with a load platform. The bottom of the pushrod is fitted with a soft rubber wiper. Initially, a tight-fitting reinforced hard-rubber wiper was contemplated, but the friction from the wiper-cylinder interface was too large and ruined the demonstration. The relatively light friction from the soft rubber wiper should be balanced with the weight of the platform and pushrod assembly, so that the weight added to the platform during the demonstration directly converts to the pressure seen on the gage. A portable scale with a capacity of about 100 lbs is also useful, and a calibrated bathroom scale will serve this purpose nicely.
Proceedings of the 2003 American Society for Engineering Education Annual Conference & Exposition Copyright 2003, American Society for Engineering Education
Vander Schaaf, R., & Klosky, J. L. (2003, June), "Show Me The Money!" Using Physical Models To Excite Student Interest In Mechanics Paper presented at 2003 Annual Conference, Nashville, Tennessee. https://peer.asee.org/12307
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