Schober's Physics - Teacher's Notes:

Energy Model

Links: Teacher notes for the Energy Model from the Modeling Instruction Program Student Materials for the Energy Model Teacher Notes Index Teacher Materials Index Student Materials Index E-mail Mark Schober with questions or requests Since 1990, the Modeling Instruction Program has been helping teachers attain knowledge and skills needed to benefit their students. Modeling Instruction is the only high school science program recognized as Exemplary by the U.S. Department of Education.

The teacher's notes below are to supplement the instructional notes that have been written in conjunction with the modeling project.   Over the next few years I hope to flesh out these notes more fully. If you have any questions, please feel free to contact me. Unit Goals Comments on the Scope and Sequence Lab notes and alternatives: Force vs. Displacement Lab Using an inclined board, students pull a pasco cart up the incline to a fixed height with a spring scale. As the incline gets steeper, the displacement along the ramp gets smaller and the pulling force gets larger. The students graph force vs. displacement, find that F = slope/disp., and the slope = F*displacement which equals the product of the constants in the experiment, Fg*height. Since friction is minimal, the only force we are working against is gravity; the applied force in the direction of the displacement (Energy transferred) equals the energy stored in the gravitational field. So we can define Eg = mgh and one way of energy transfer = Fx. Height vs. Speed Lab Using a section of our rollercoasters (or an inclined Pasco track) students measure the height of the cart above a level tabletop and the velocity of the car at each height with a photogate. The students see as the height decreases, the velocity increases. To get a direct relationship they graph change in height vs. speed and eventually develop the relationship v^2 = (20 m/s^2)*h = 2gh. Using our definition for Eg, the expression for Ek is derived. Spring compression vs. Speed lab (or spring compression vs. height if an inclined track is used.) Using a 10cm diameter loop of spring steel attached to the end of the pasco track, the students first find the spring constant of the loop, then they find the relationship between spring compression and the shoot velocity, measured with a photogate. From the equation for their graph and the definition of Ek, the students can determine the expression for Eelastic. For the rollercoaster lab I bought Pasco's rollercoaster kit without the support boards and several extra tracks. Each group gets one cart, 4.5 meters of track, 20 or so blue track pegs that have been jammed over pegboard hooks, 20 white track clips, and a 2' x 8' piece of pegboard, supported with ring stands. A third ring stand is used to support a photogate to measure velocities of the rollercoaster throughout the ride. The kids take a class period to get a rollercoaster to work with at least one hill and one loop. Then they make measurements at a variety of places along the track and analyze the forces and dissipated energy throughout the ride. I really like the lab, although it's tricky to schedule because just one class can use the setup at a time and it takes multiple days for the students to build and then collect data. Photos of the student rollercoasters are posted at http://www.jburroughs.org/science/mschober/photos/photos.html Comments on worksheets Assessment