Student Exploration: Energy Conversions in a System

Student Exploration: Energy Conversions in a System Prior Knowledge Questions (Do these BEFORE using the Gizmo.) 1. What are some examples of devices that are powered by batteries? A calculator, batteries, flashlight 2. What different forms of energy are demonstrated by these devices? Most of them demonstrate kinetic or electrical energy Gizmos Warm Up Energy constantly changes from one form to another, but in a closed system, the total amount of energy always remains the same. This concept is known formally as the law of conservation of energy. The Energy Conversion in a System Gizmo allows you to observe the law of conservation of energy in action. In the Gizmo, a suspended cylinder has gravitational potential energy. When the cylinder is released, the gravitational potential energy is converted into kinetic energy, which causes the stirrer in the water to spin. 1. What is the initial temperature (T) of the water? 25 celsius 2. Click Play ( ). What happens as the cylinder drops? The temperature increases and the cylinder decreases in height as it lowers from the original position in mid air. 3. What is the final temperature of the water? 29.69 celsius 4. Why do you think the temperature of the water increased? I think that the movement created by the little turbine fan within the beaker transferred more kinetic energy which adds heat energy to the water. Page 1 of 3 This study source was downloaded by from CourseH on :12:24 GMT -06:00 Student Exploration: Energy Conversions in a System Introduction: The raised cylinder in the Gizmo has gravitational potential energy (GPE) because gravity can cause the cylinder to drop. When the cylinder drops, its kinetic energy is converted into heat energy, which raises the temperature of the water. Question: How does the cylinder’s initial height affect its gravitational potential energy? 1. Predict: How do you think increasing the cylinder’s height will affect the final temperature of the water? If you increased the original height in which the cylinder is positioned at then maybe the higher the cylinder is the harder it will fall producing more heat than when it was lower. 2. Gather data: Make sure the water’s Mass is 1.0 kg, its Temp is 25 °C, and the cylinder’s Mass is 5 kg. Set the cylinder’s Height to 100 m. (Note: The large height scale used by the Gizmo, while not practical in a real-world experiment, makes it easier to produce observable temperature changes in the water.) Click Play, and record the water’s final temperature in the table below. Repeat the experiment at each cylinder height to complete the second column in the table. Cylinder height (m) Final temp. (˚C) Change in temp. (˚C) Cylinder GPE (J) 100 m 26.17c 1.17c 4900j 200 m 27.34c 2.34c 9800j 500 m 30.86c 5.86c 24,500j 1,000 m 36.72c 11.72c 49,000j 3. Calculate: Subtract the water’s initial temperature from its final temperature to complete the third column of the table. An object’s GPE can be calculated by multiplying its height (h) by its mass (m) and acceleration due to gravity (g): GPE = mgh. On Earth, g = 9.8 m/s2 . Calculate the cylinder’s GPE for each of the trials you completed and fill in the last column of the table. 4. Analyze: Study the data you collected. A. How does doubling the height of the cylinder affect its GPE? Doubling the height will increase the amount of joules produced Page 2 of 3 This study source was downloaded by from CourseH on :12:24 GMT -06:00 Student Exploration: Energy Conve