What Would Make a Card Jump? How Can You Observe Evidence to Draw Conclusions That Energy Is Transformed?
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Name Class Date What Would Make a Card Jump? How can you observe evidence to draw conclusions that energy is transformed? Background Energy is needed to cause an object to start moving, stop moving, speed up, slow down, or change direction. This energy can be transformed from other kinds of energy. In this activity, you will observe energy transformations. Materials (per pair) • 3 × 5 index card • scissors • rubber band Safety Be sure to follow all safety procedures provided by your teacher. Find more information about the safety icons in the Safety Section. Procedure c 1. Fold an index card in half. c 2. In the edge opposite the fold, cut two slits that are about 2 cm long and 2 cm apart. The slits should be cut through both halves of the card. c 3. Keep the card folded and loop a rubber band through the slits. With the fold toward you, gently open the card like a tent and flatten it against your desk. c 4. Predict what will happen to the card if you let go. Then test your prediction. Think It Over 1. Make Observations Describe what happened to the card. uConnect Lab Copyright © Pearson Education, Inc., or its affiliates. All Rights Reserved. Name Class Date 2. Cite Evidence Based on your observations, use evidence to describe the forms of energy observed in this activity and the changes in energy that took place. 3. Predict What can you do to increase the potential energy of a rubber band? uConnect Lab Copyright © Pearson Education, Inc., or its affiliates. All Rights Reserved. Name Class Date What Work Is How can you construct an argument that relates the change in an object’s energy to work? Background Think about the last time you made something move by pushing or pulling it. Perhaps it was a heavy box or a piece of furniture. To make the object move, you had to put some effort into it. That is, you spent some energy to do some work. When you do work on an object, some of your energy is transferred to that object. So, you can also think of work as the transfer of energy. When energy is transferred, the object upon which the work is done gains energy. In this activity, you will contrast situations where work is done. Then you will construct an argument relating energy to work. Materials (per group) • plastic funnel • small gravel • soda can with tab • tape measure • spring scale • masking tape • string, 40 cm • pulley Safety Be sure to follow all safety procedures provided by your teacher. Find more information about the safety icons in the Safety Section. Procedure c 1. Put on your goggles. Use a funnel to put gravel into the soda can until the can is about half full. Immediately pick up any gravel that falls on the floor. Thread the string through the tab of the can. Tie the ends together to make a loop. c 2. Make Measurements Use the spring scale to measure the force it takes to lift the can. Record the force in newtons (N). c 3. Make Measurement Use the tape measure to measure the distance from the floor to the tabletop. Record your measurement in meters (m). c 4. Place the can on the floor, and lift it until the bottom edge meets the tabletop. c 5. Make Measurements Use the masking tape to mark a two-meter distance on the floor. Walk two meters while carrying the can. uInvestigate Lab Copyright © Pearson Education, Inc., or its affiliates. All Rights Reserved. Name Class Date c 6. Make Measurements Use the pulley to lift the can. Use the spring scale to determine the force it takes to lift the can. Record the force in newtons (N). Analyze and Interpret Data 1. Use Mathematical Representations Calculate the amount of work you did in Step 4. Remember that you will need to multiply the distance you measured with the tape measure and the force you measured with the spring scale. The unit for work is the joule. 2. Describe In which direction did you pull on the can in Step 4? In which direction did the can move? In which direction did you pull on the can in Step 5? In which direction did the can move? 3. Reason Quantitatively Contrast (1) the situation in Step 5, in which you walked while holding the can, with (2) the situation in Step 4, in which you lifted the can, and (3) the situation in Step 6, in which you used a pulley to lift the can. Explain why you did different amounts of work in the different steps. 4. Construct an Argument Present an argument to support or refute the claim that the energy of the can did not change in Step 6. Use empirical evidence and scientific reasoning relating work to energy in your argument. uInvestigate Lab Copyright © Pearson Education, Inc., or its affiliates. All Rights Reserved. Name Class Date Mass, Velocity, and Kinetic Energy How can you use a skateboard to model how a constant kinetic energy changes velocity when mass changes? Background Look around you. You will probably see objects in motion, such as other students writing, someone walking down the hallway, or pencils falling. But if two students who do not weigh the same walk at the same velocity, do they have the same amount of kinetic energy? In this activity, you will observe how a constant kinetic energy affects velocity when mass varies. Materials (per group) • skateboards or toy trucks • three large books • measuring stick Procedure c 1. Place one book on the skateboard. c 2. Make Observations Push the skateboard, and observe the velocity at which the skateboard travels. c 3. Plan Your Investigation Design a procedure to test how mass affects the velocity of an object if the object’s kinetic energy remains constant. (Hint: Measure the velocity of the skateboard while varying its mass.) Use only the materials provided. Write your procedure below. Have your teacher approve your plan. c 4. Construct Tables After your teacher has approved your plan, construct a table in which you will record your data. Use the space provided at the end of this Procedure section, or you may use your lab journal or science notebook. Be sure to add titles and appropriate labels for columns and rows. Also, include the correct metric units in your data table. Use the following hints to help you organize your data. • What type of data will you be collecting? Will it be quantitative or qualitative? • What tests will you perform? • How many trials will you perform? • What variable(s) will you change? What variable(s) will you keep constant? uInvestigate Lab Copyright © Pearson Education, Inc., or its affiliates. All Rights Reserved. Name Class Date c 5. Conduct an Investigation Carry out your investigation and record your data in your table. Data Table Analyze and Interpret Data 1. Compare Data What can you infer about the magnitude of the kinetic energy of the skateboard in your various trials? Explain. 2. Compare Data How do the velocities in the trials compare? Explain. 3. Identify Variables What quantity was kept constant in this experiment? What quantities varied? uInvestigate Lab Copyright © Pearson Education, Inc., or its affiliates. All Rights Reserved. Name Class Date 4. Use Mathematics The equation below expresses the proportional relationship between an object’s kinetic energy, mass, and velocity. Kinetic energy = ½ x mass x velocity2 How did your observations confirm this equation? 5. Predict Suppose you determined the skateboard’s velocity while carrying 1, 2, 3, and 4 books. Then suppose you constructed a line graph with mass (number of books) on the x- axis and velocity on the vertical y-axis. What do you think the graph line would look like? Explain. uInvestigate Lab Copyright © Pearson Education, Inc., or its affiliates. All Rights Reserved. Name Class Date Making a Flashlight Shine What are some different types of energy? Background There are many different types of energy all around you. Imagine walking down the street on a sunny day listening to music on a digital audio player. Light energy, electricity, heat, and energy of motion are just some of the types of energy involved in this activity. In this lab, you will observe different types of energy at work when you operate a flashlight. Materials (per group) • flashlight • batteries Procedure c 1. Remove the batteries from a flashlight and examine them. Think about what type of energy is stored in the batteries. (Hint: When the batteries are connected to the flashlight, and you turn the flashlight on, an electric circuit is completed.) c 2. Replace the batteries and turn on the flashlight. What do you observe? c 3. Make Observations After a few minutes, place your hand near the bulb of the flashlight. What do you observe? Analyze and Interpret Data 1. Identify What types of energy are involved when a flashlight shines? 2. Apply Concepts Describe how you think energy flows through a flashlight’s system. uInvestigate Lab Copyright © Pearson Education, Inc., or its affiliates. All Rights Reserved. Name Class Date 3. Construct Explanations Describe how the flashlight either releases or absorbs thermal energy. Explain how you know. 4. Infer What role do chemical processes play in the operation of the flashlight? 5. Form a Hypothesis Do you think matter is lost or conserved when you use a flashlight? Explain. 6. Apply Scientific Reasoning How could you modify the flashlight to increase the amount of energy it releases? uInvestigate Lab Copyright © Pearson Education, Inc., or its affiliates. All Rights Reserved.