HW 1.doc

Homework #1 Group Assingment ChBE 201 Winter 2008 Due Friday, January 11, 5 PM @ Carmen Drop Box For you first group homework assignment you will help out the GK-12 and WOW outreach programs at OSU. We have been asked to design an experiment or demonstration for the concept of conservation of energy for a middle school (Grade 7) classroom. This experiment should meet two or more of the following goals : Describe how an object can have potential energy due to its position or chemical composition and can have kinetic energy due to its motion. Identify different forms of energy (e.g., electrical, mechanical, chemical, thermal, nuclear, radiant, and acoustic). Explain how energy can change forms but the total amount of energy remains constant. Trace energy transformation in a simple closed system (e.g., flashlight). Your homework will consist of two parts: (A) A written procedure for an experiment that meets two or more of these goals. (B) A worksheet that students will fill out in response to observations Examples are provided below. Please follow the format provided. Experiments will not be demonstrated in class, but must be realistic. They should be capable of being accomplished in a 45 minute time frame, use materials that are inexpensive or readily available in an average middle school classroom, and be safe to conduct in a middle school setting. All work should be typewritten. It should include all group members? names. It should also include the mailbox # of the scribe so that it may be returned after grading. Soft copies should be uploaded to the Carmen dropbox by the 5 PM Friday. As this assignment will be turned in digitally, listing your name implies contribution to and agreement with the work handed in. Example Experimental Procedure Title: Energy Conservation Using a Roller Coaster Model Purpose: This experiment will demonstrate the educational concepts of: Describe how an object can have potential energy due to its position or chemical composition and can have kinetic energy due to its motion. Identify different forms of energy (e.g., electrical, mechanical, chemical, thermal, nuclear, radiant, and acoustic). Explain how energy can change forms but the total amount of energy remains constant. Trace energy transformation in a simple closed system (e.g., flashlight). by demonstrating how a roller coaster acquires potential energy and then dissipates that energy to scale a bump, identify two forms of energy (kinetic and potential), explain how energy remains constant and trace energy transformation by tracing the conversion of kinetic to potential energy. Additionally, the concept of heat (friction) as a means of energy transfer will be discussed to account for energy lost in the kinetic to potential conversion. Materials: Roller coaster track with a bump Roller coaster Ruler Stop watch Safety Considerations/PPE: Roller coasters may pinch fingers; caution should be used during operation. Otherwise, no special equipment is required. Procedure: Teams should each obtain one roller coaster track equipped with bump, 1 ruler, and 1 stop watch. Teams should measure the height of the bump in the track and determine the amount of kinetic energy that may be required to scale the bump assuming all kinetic energy were converted to potential energy. Teams should estimate the speed that a roller coaster would travel from the bump the end of the track assuming all potential energy were converted into kinetic energy. Teams should measure the distance from the top of the bump to the end of the tracks that a roller coaster would travel. Teams should then place their roller coasters on the bump and allow them to fall down the track measuring the time it takes to traverse the distance from the center of the bump to the end of the track with the stop watch. This should be repeated several times (e.g., 5) and the data should be averaged to obtain an average value. Example Worksheet Worksheet for ?Energy Conservation Using a Roller Coaster Model? 1. What is the height of your roller coaster track bump? 2. What is the potential energy of a roller coaster relative to the bottom of the track when it is on the bump? 3. What kinetic energy would be required to surmount the bump starting at the beginning of the tracks? 4. If the roller coaster was pushed off the bump, what would the average velocity be at the bottom of the tracks? 5. What is the distance from the middle of the bump to the bottom of the tracks? 6. What is the average speed (measured) of the roller coaster as it descends the bump? Trial Average Speed 1 2 3 4 5 Average Thought Questions: 1. How closely do your measured speeds agree with your experimental prediction? Why or why not? Instructor Note: Chance to discuss friction (heat) as a mode of energy transfer. 2. Trace energy through out the process. Instructor Note: This process should demonstrate types of energy, their conservation and trace the path of energy conversion/transfer. Ohio Department of Education, Academic Content Standards, K-12