5BL Lab 1 Manual - W24v2

Physics 5BL Lab 1 Manual: Thermal Energy & Temperature Winter 2024, UCLA Department of Physics & Astronomy Lab Procedure 1. As a first step, measure the temperature of the environment (ambient temperature), the human body temperature (both forehead and under the tongue), and two other objects in the room. Record this information in both Fahrenheit and Celsius units, and group the items into a category of either being in equilibrium with the environment, or not in equilibrium with the environment. Using the human body as the system, explain the direction of heat flow between the body and the environment. Explain how you know the direction of this heat flow. (Use the IR (yellow) thermometer for objects that are not a human’s face, the head thermometer for a human’s forehead, and the under-tongue thermometer to measure a person’s core body temperature. There are single use covers for the under-tongue thermometer.) 2. As an investigation of scientific question A (see above), use the IR temperature gun to measure the temperature of your hands both before and after vigorously rubbing them together (note the frictional resistance to the kinetic energy of the hand motion!). Compare the temperature difference (if any) before and after, and relate this to how the temperature change is providing information about how energy is changing form through the use of our body’s conversion of food to the chemical energy that fuels the motion of our muscles. Roughly how long does it take for your hands to get back to equilibrium, and what process allows that to occur? 3. As an investigation of scientific question B, choose an object that is not the human body, but that also has a consistently higher temperature than the environment temperature. Describe how thermal energy should be changing in the object as time goes on (given the direction of heat flow). Given this direction of heat flow, how would you expect the temperature of the object to change with time? How is it able to stay at a hotter temperature than the surroundings, even though heat is constantly flowing? Given that energy is always conserved when one takes a large enough perspective, what is the energy flow process that allows the hot object to stay hot? Now, relate this to the temperature measurements taken of the human body, and create an explanation for how our human body is able to consistently maintain a hotter temperature than the environment. 4. Use either a human body, electronic devices, and/or light bulbs to take two (2) ‘FLIR’ images. Capture a copy of these with your phone (don’t need to upload any photos from the ‘FLIR’ camera), and add these photos to your assignment for analysis. Describe the heat flow information provided by this picture, including information about the flow of thermal energy. Explain how the total energy in time is constant, and describe how the energy is changing form as the heat flows. Identify the hottest and coolest objects in each of your images. Feel free to draw and upload an additional diagram to supplement your explanations, if the IR camera is available at the end of your lab. You can read more about how thermal imaging works here .