Lab #4 - 1st Law of Thermodynamics

Saturday, February 10, 2024 Lab #4 - 1st Law of Thermodynamics You will use this worksheet as you work your way through the lab activity and submit it on CANVAS will all fields completed. Learning Outcomes:  Quantify the relationship between heat energy transferred to a system and the change in temperature of the system Validate the value of the Universal Gas Constant from experimental data.  Understand the specific heat meaning and how to measure it. Supplies:  Access to the PhysicsLE Lab Simulation Software – First Law of Thermodynamics Simulation: Joule's Experiment  Blank paper and pencil for handwriting the work for your calculations. Background: Heat energy transfer occurs when two different temperature substances are in thermal contact. There are additional methods for heat energy to transfer. An example is rubbing your hands together vigorously. Mechanical energy used to move your muscles and rub your hands together caused an increase in temperature between your hands. Experiments observed by scientists concluded heat is another form of energy, flowing from one temperature difference to another between two objects. One experiment used by James Joule to observe heat transfer is demonstrated by a falling mass rotating a paddle within an insulated cylinder containing water. The water will increase in temperature and at a predictable amount. The experiment is idealized (no energy loss to the surrounding environment, massless and frictionless pulleys, and no energy absorbed by the stirring mechanism). You are fortunate, in the lab there will be a histogram displaying the gravitational potential energy of the falling mass and the change in thermal energy of the water. Procedure: Part 1: 1. Start the First Law of Thermodynamics Simulation: Joule's Experiment. 2. Run #1 a. Set the Block Mass to 2.0 kg using the slider (move to the left) b. Press Play c. Record the Temperature change and the change in Thermal Energy in Table 1. d. Calculate the Temperature change per unit of heat energy and record it in the table. 1

Saturday, February 10, 2024 i. Show three significant figures to the right of the decimal place for your calculations. 3. Run #2 a. Set the Block Mass to 5.0 kg using the slider (move to the left) b. Press Play c. Record the Temperature change and the change in Thermal Energy in Table 1. d. Calculate the Temperature change per unit of heat energy and record it in the table. i. Show three significant figures to the right of the decimal place for your calculations. 4. Run #3 a. Keep the Block Mass at 5.0 kg but decrease the Water Mass to 2.5 kg. b. Press Play c. Record the Temperature change and the change in Thermal Energy in Table 1. d. Calculate the Temperature change per unit of heat energy and record it in the table. i. Show three significant figures to the right of the decimal place for your calculations. 5. Run #4 a. Keep the Block Mass at 5.0 kg, and the Water Mass at 2.5 kg. This time you will decrease the Initial Water Temperature to 10°C. b. Press Play c. Record the Temperature change and the change in Thermal Energy in Table 1. d. Calculate the Temperature change per unit of heat energy and record it in the table. i. Show three significant figures to the right of the decimal place for your calculations. Table 1: Part 1 Data Run Mass of Water (kg) Initial Water Temperature (°C) Final Water Temperature (°C) Temperature Change ΔT (°C) Total heat delivered to Water ΔQ. (J) Temperature changes per unit of heat energy (°C / J) 1 5.0 20.0 Click or tap here to enter text. Click or tap here to enter text. Click or tap here to enter text. Click or tap here to enter text. 2 5.0 20.0 Click or tap here to enter text. Click or tap here to enter text. Click or tap here to enter text. Click or tap here to enter text. 3 2.5 20.0 Click or tap here to enter text. Click or tap here to enter text. Click or tap here to enter text. Click or tap here to enter text. 4 2.5 10.0 Click or tap here to enter Click or tap here to enter Click or tap here to enter Click or tap here to enter text. 2

Saturday, February 10, 2024 Part 2: 6. Reset the simulation. 7. Run A a. Run the simulation and record the temperature change, and total heat delivered to the water, and calculate the specific heat. Record the values in Table 2. 8. Run B a. Decrease the mass of the water to 1.0 kg. b. Run the simulation and record the temperature change, and total heat delivered to the water, and calculate the specific heat. Record the values in Table 2. 9. Run C a. Reset the Water Mass to 5.0 kg. b. Decrease the Initial Height to 50 m. c. Run the simulation and record the temperature change, and total heat delivered to the water, and calculate the specific heat. Record the values in Table 2. 10. Run D a. Reset the Initial Height to 100 m. b. Increase the Temperature to 50 °C. c. Run the simulation and record the temperature change, and total heat delivered to the water, and calculate the specific heat. Record the values in Table 2. Table 2: Part 2 Data Run Mass of Water (kg) Temperature Change ΔT (°C) Total heat delivered to Water ΔQ. (J) Water Specific Heat (J / (kg * Δ °C)) A 5.0 Click or tap here to enter text. Click or tap here to enter text. Click or tap here to enter text. B 1.0 Click or tap here to enter text. Click or tap here to enter text. Click or tap here to enter text. C 5.0 Click or tap here to enter text. Click or tap here to enter text. Click or tap here to enter text. D 5.0 Click or tap here to enter text. Click or tap here to enter text. Click or tap here to enter text. 4

Saturday, February 10, 2024 Post Lab Questions: 1. Review the results from Run #1 vs. Run #2 – Explain what happened when you increased the mass of the black from 2.0 kg to 5.0 kg. Click or tap here to enter text. 2. Summarize the results when you decreased the Water Mass in Run #3. Explain why you got the results you did. Click or tap here to enter text. 3. Based on your data in Table 1, explain how the math relationship works by highlighting the role of each variable. ΔQ = c * m * ΔT Where: ΔQ = heat energy transferred to the water m = mass of the water ΔT = change in temperature c = constant characteristic of the liquid Click or tap here to enter text. 4. Calculate the average specific heat of water from the values in Table 2. Include units in all your answers. Click or tap here to enter text. 5. How closely did the specific heat of water values you got agree with each other in Table 2? Be specific and provide values or percentages from your results and explain why you see differences. Click or tap here to enter text. 6. How far off is your average value for the specific heat of water from the accepted value of 4,190 J / (kg * Δ °C) for water? Click or tap here to enter text. 7. What are the possible sources of experimental error that might explain any disagreement? Click or tap here to enter text. 5