Student Exploration_ Density GIZMO ANSWER KEY

1. List three objects that you think would sink in water, and three objects you think would float. Sink: An egg, a penny, and a rock. Float: A ping pong ball, an air-filled balloon, a boat 2. Why do you think some things float and some things sink? Some things float and some things sink because it all depends on how much matter is inside the object that you’re using. Gizmo Warm-up 1. In the Gizmo, drag the apple onto the Scale. The scale measures mass. Mass is the amount of matter, or “stuff,” in an object. What is the apple’s mass? (Note: “g” stands for grams.) 33g 2. An object’s volume is the amount of space it takes up. The volume of an object can be measured by using a graduated cylinder. Observe the graduated cylinder and the blue text showing the volume of water inside the cylinder. A. What is the starting volume of water in the graduated cylinder? 400mL B. Place the apple into the cylinder. What is the volume in the cylinder now? 444mL The water rises in the cylinder because it is displaced, or pushed upward, by the apple. The amount of displaced water is equal to the volume of the apple. C. What is the volume of the apple? (Use the Object volume to check.) 44cm3 Note: Milliliters (mL) are used for liquid volumes, while cubic centimeters (cm3 ) are used for solids. One mL is the same volume as one cm3 . The apple’s volume is measured in cm3 . Reproduction for educational use only. Public sharing or posting prohibited. © 2020 ExploreLearning™ All rights reserved This study source was downloaded by from CourseH on :37:43 GMT -05:00 Activity A: Sink or float? Get the Gizmo ready: ● Replace all objects on the shelf. ● Be sure the liquid in the beaker is Water. Question: How do mass and volume affect sinking and floating? 1. Predict: Which objects do you think will float in water? Which do you think will sink? Record your predictions below in the first column of the table. Object Prediction (sink or float?) Mass (g) Volume (cm3 ) Result (sink or float?) Ping pong ball float 3g 36 float Golf ball sink 45g 36 sink Chess piece float 40g 80 float Penny float 3g .4 sink Rock sink 200g 50 sink 2. Experiment: Use the Gizmo to find the mass and volume of each object and whether it floats or sinks. Record your results in the table. 3. Analyze results: Look at the data in your table. A. Can you use mass alone to predict whether an object will sink or float? Explain. No, because there isn't a pattern in the numbers. the penny and the ping pong ball both have the same amount of mass, but the ping pong ball floats, and the penny sinks. B. Can you use volume alone to predict whether an object will sink or float? Explain. No, because there isn't a pattern in the numbers. the ping pong ball in the golf ball has the same value but the ping pong ball ends up floating and the golf ball ends up sinking. 4. Draw conclusion: Can you use mass and volume to predict whether an object will sink or float in water? Explain your thinking. yes because there is a pattern. If the mass is greater than the volume the object will sink, if the mass is less than the volume the object will float. 5. Apply: Measure the mass and volume of the toy soldier. Mass: 120g Volume: 80 Reproduction for educational use only. Public sharing or posting prohibited. © 2020 ExploreLearning™ All rights reserved This study source was downloaded by from CourseH on :37:43 GMT -05:00 Will it float or sink? sink Use the Gizmo to test your prediction. Activity B: Calculating density Get the Gizmo ready: ● Replace the objects on the shelves. ● Be sure the liquid in the beaker is Water. Question: How does density tell you whether an object will sink or float? 1. Calculate: Density is the amount of mass contained in a given volume. To find the density of an object, divide its mass by its volume. Density is recorded in units of grams per cubic centimeter (g/cm3 ). What is the density of an object with a mass of 100 g and a volume of 50 cm3? 2 g/cm3 2. Record data: In the Gizmo, find mass and volume of the objects listed below. Then calculate each object’s density and record it. Finally, test whether each one sinks or floats in water. Object Mass (g) Volume (cm3 ) Density (g/cm3 ) Sink or Float? Chess piece 40 80 0.5 float Rock 200 50 4.0 sink Toy soldier 120 80 1.5 sink Apple 33 44 0.75 float 3. Draw conclusion: The density of water is 1.0 g/mL, or 1.0 g/cm3 . Look at the data in your table. How can you use the density of an object to predict whether it will sink or float? An object will sink in water if the density is 1.0 g/mL or 1.0 g/cm3 It will float if it has a density of less than 1.0 g/cm cubed. 4. Apply: In the Gizmo, either Crown 1 or Crown 2 is solid gold (but not both). Find the density of the gold nugget and of each crown. (Hint: You will probably need a calculator to do this.) A. Density of the gold nugget: 19.3 g/cm3 Reproduction for educational use only. Public sharing or posting prohibited. © 2020 ExploreLearning™ All rights reserved This study source was downloaded by from CourseH on :37:43 GMT -05:00 B. Density of Crown 1: 8.4 g/cm3 C. Density of Crown 2: 19.3 g/cm3 D. Which crown is pure gold? Crown 2 has the same density as the gold nugget so it is the one that is pure gold.