Teacher Guide Including Student Activities Module 1: Tracing Energy Transformations
ACTIVITY GUIDE Module 1: Tracing Energy Transformations Summary: We use energy on a daily basis. We use it to make our coffee and power the cars we drive to work. Virtually everything in the modern world requires an outside power source. The production of that energy involves a transformation, an energy transformation. An example of energy transformation is found in the cars we drive. When a battery is used to start the car, energy is converted from electrical to mechanical energy. To move the car, chemical energy in the form of gasoline converts to mechanical energy. Each transformation leads to the production of heat. Feel the tires after a long trip; they are warm from friction. Feel the hood of the car; it is warm from the radiant heat of the engine. Unbelievably, almost everything we do involves an energy transformation. Look at an energy system and trace the energy transformations occurring inside. For this example, think of it as a closed system where no energy is lost to the environment. For example, we could trace the energy transformations within a system such as the MG automobile mentioned in the video. Consider the transformation of chemical energy to electrical energy to mechanical energy to start the car. We might first see a battery that represents stored chemical energy waiting to be converted to electrical energy. Next, within this system, we might see two wires connecting the battery to an electric motor; this could represent the electricity being transferred to the electric motor. Tracing through the system, we might next see the shaft from the motor turning a series of gears; this represents the transformation of electric energy to mechanical energy. Objective: Explain how energy may change form or be redistributed but the total quantity of energy is conserved. Module 1: Segment Length 10:05 minutes Page 2
Ohio Standards Connection: Grade Nine Physical Science Benchmark F: Explain how energy may change form or be redistributed but the total quantity of energy is conserved. Organizer: Indicator 15: OSIC Nature of Energy Trace the transformations of energy within a system (e.g., chemical to electrical to mechanical) and recognize that energy is conserved. Show that these transformations involve the release of some thermal energy. Y2003.CSC.S03.G09-10.BF.L09.I15 Suggestions for the teacher: 1. Preview each segment before showing. 2. Prepare the class and gather all necessary materials. 3. Review segment content with class at each pause screen. 4. Begin lesson sequence activity after viewing lesson. Safety: Always be careful! Teachers and students should always exercise appropriate safety precautions and utilize appropriate laboratory safety procedures and equipment when working on science performance tasks. Page 3
Activity: Rebound Height Measurements Students working in teams of four will measure the rebound heights of a tennis ball dropped from four different heights. Students will be investigating the energy transformations of the bouncing balls. Notes to teacher: Instruct students to focus on the energy in the ball not the energy of the athlete. Assign students to act as data recorders and observers as the trials take place. Materials: 1 tennis ball 1 meter stick 2 sheets of scrap paper for recording data Procedures: 1. Tape the meter stick to the wall or any stable vertical surface with 0 cm at the bottom. 2. Drop the tennis ball from each of the different heights three times as shown on the chart. 3. Take the measurement of the rebound. Be sure to use the bottom edge of the ball for your measurements. Sit on the floor directly in front of the meter stick and be ready to watch the ball bounce. 4. The observer will record the data. Conduct the trials and record the rebound height measurement of each ball on the "Ball Rebound Heights" data chart. When the trials have been completed, students should copy the data onto their own data charts. Page 4
Data Chart: Starting Height Ball Rebound Heights Chart Trial 1 Trial 2 Trial 3 100 cm 80 cm 60 cm 40 cm Page 5
Activity Questions: It has been stated that a ball will not bounce back to the starting height no matter what the starting position might be. Using evidence from the investigation, explain whether you think this statement is true. In this investigation, the starting height and the rebound height of the ball were measured. Look at the type of energy the ball had at different times. A. Identify the kind of energy the ball had when held at 100 cm. B. Explain your answer. C. Identify when the ball has kinetic energy. D. Suppose the rebound height of a ball was 80 cm when its starting height was 100 cm. Explain what caused the difference in the amount of energy in the ball before it dropped and when it rebounded. Page 6
E. Use the graph constructed to help decide the rebound height measurement one would predict if the ball was dropped from a height of 120 cm. Write your prediction here: cm F. Explain how you arrived at this prediction. Page 7
Quiz: Tracing Energy Formations In the video when the basketball is shot, it continues to climb for a brief time period until it reaches the top of its arc. Which graph describes the kinetic energy of the basketball until it reaches its peak? Commentary: This multiple-choice question asks students to recognize the graph that shows the kinetic energy of the basketball during the first few moments of flight. Students must bring together their understanding of acceleration, kinetic energy and information given in the scenario to graphically show how the kinetic energy of the basketball will change over time. The kinetic energy associated with the basketball is directly proportional to the product of its mass and speed squared at any point in time (KE = ½ mv 2 ) during its motion. Since a basketball shot is from rest, the initial shuttle speed = 0, and the ball continues to gain speed during the first few moments of flight. Answer choice A is correct. Based on the given information, this graph correctly shows the initial kinetic energy equal to zero and correctly depicts the increasing kinetic energy over the first few minutes. Answer choice B is incorrect. Based on the given information, the kinetic energy (and speed) would not increase from zero to a maximum and then decrease to zero in the first few minutes as this graph shows. Two answer choices C and D are both incorrect as the initial kinetic energy of the shuttle is not greater than zero at time = 0 as both graphs show. This error in data representation alone rules out both choices. Page 8
Ohio Content Provider Recommendations: Search String: kinetic energy potential energy acceleration energy transformations conservation of energy Additional curricular resources can be found at the following websites using one or more of the search strings listed above to narrow your search. INFOhio http://www.infohio.org/ Ohio Resource Center http://ohiorc.org/ Ohio Department of Education http://ims.ode.state.oh.us/ode/ims/lessons/ Finding Additional Resources Using D3A2: The D3A2 website helps educators analyze data, and points them to resources such as lesson plans, assessments and activities designed specifically to address the academic need identified by the data. In addition to linking content to data analysis, educators will have general search capabilities to locate education content resources aligned to the Ohio s Academic Content Standards. Sample D3A2 Standard Search Results: Energy Tracer - Grade Nine: Retrieved from the Ohio Department of Education o http://ims.ode.state.oh.us/ode/ims/lessons/web_content/csc_lp_s 03_BF_L09_I15_01.doc Page 9