Heat Absorption

Name: ________________ Date: __________ Student Exploration: Heat Absorption Voc:;abulary: absorb, greenhouse, radiation, reflect, thermal energy Prior Knowledge Questions (Do these BEFORE using the Gizmo.) 1. Is it usually hotter outside when the Sun is low in the sky, such as early in the morning, or when the Sun is high in the sky, around noon? _______________ 2. If you want to stay cool on a hot, sunny day, should you wear black or white? Why? Gizmo Warmeup In the Heat Absorption Gizmo rM , a powe1ful flashlight can shine on a variety of materials. Make sure that the Light color is set to White. 1 . Drag the Wood under the beam of light What do you notice? ________________ 2. What is the color of the light that is reflected off the wooden block? ________ 3. Click Play (,�)to start the clock. A. What happens to the temperature of the wood? ____________ B. The light that is not reflected away is absorbed by the wood. What does the absorbed light energy do to the wood? _______________ Energy that is transmitted through space by light waves is called radiation. The wood gets hotter because it gains thermal energy from the light waves. Activity A: Get the Gizmo ready: Angle of light • Click Reset (.2,,). • Check that Light color is still set to White. • If necessary, drag the Wood under the light. Question: How does the angle of light affect heating? 1. Observe: Drag the flashlight to several different angles. When is the light beam most concentrated on the piece of wood? ___________________ 2. Form hypothesis: How will the angle of light affect how much the piece of wood is heated? 3. Predict: Which angle will result in the hottest piece of wood? ___________ 4. Experiment: For each angle listed below, record the final temperature of the wood after 3 hours of heating with the flashlight. 20 ° angle 40 ° angle 60° angle 80 ° angle 90° angle Final temperature 5. Draw conclusions: Why did increasing the angle of the beam of light cause the wood to heat up more? __________ _______________ ____ 6. 8Q.ply: St. Louis, Missouri, is located near the middle of the United States. On June 21, the noon Sun rays hit St. Louis at an angle of 75 ° . On December 21, the noon Sun rays hit at an angle of 28 ° . How will this affect the temperature in St. Louis on these dates? Activity B: Colored materials Get the Gizmo ready: • Click Reset. • Drag the flashlight so that the Light angle is 75 ° . Question: How do colored materials absorb and reflect light? 1. Observe: Drag the red brick under the flashlight beam. Try three different Light colors: red, blue, and green. A. What color(s) reflect off a red brick? ____________ ____ _ B. What colors of light are absorbed by the brick? _____________ 2. Predict: Predict what color(s) of light will .heat the red brick the most and the least. Most heating: ______ ____ Least heating: _ __ _______ 3. Collect data: Heat the red, gree11, and blue bricks under each color of light. Record results. Red light Blue light Green ligllt Red brick final temperature Green brick final temperature Blue brick final temperature 4. Analyze: Based on your data, what light colors were absorbed and reflected by eacl1 brick? Red brick reflects _____ light, absorbs _____ and _____ light. Green brick reflects _____ light, absorbs _____ and _____ light. Blue brick reflects _____ light, absorbs _____ and _____ light. 5. Extend your thinking: White light is a combination of red, green, and blue light. Why is it cooler to wear a white shirt on a sunny day than a black shirt? Activity C: Comparing materials Get the Gizmo ready: • Click Reset. • Change the Light color to white. Question: Which materials are easiest to heat up? 1. Predict: In this activity you will compare how metal, wood, water, and brick heat up. A. Which substance do you think will heat up the most? ___________ B. Which substances will heat up the least? _______________ 2. Experiment: Using white light, heat up each of the following substances for 3 hours. Metal Wood Water Black brick White brick Final temperature (no glass cover) .. 3. Analyze: Based on the results, which substances do you think reflected the most light? 4. Experiment: A greet:thouse is a building with a glass roof and walls. Light can get in, but the heated air inside cannot escape. Click Add glass cover to simulate conditions in a greenhouse, and heat up each substance. Record your results below. Metal Wood Water Black brick White brick Final temperature (under glass) 5. Analyze: What effect did the glass cover have? _______________ 6. Extend your thinking: Why is it dangerous to leave an infant or pet in a car on a sunny day with the windows rolled up?