Activity 2 Interactions and Motion Energy Activity 2: Interactions and Motion Energy Use How To Identify Interactions to create and complete a interactions chart for the 11 events described below. Use the following chart as a model. One example interaction has been completed for you. Example: A child pushes a toy car that was sitting on the floor. 1. A person pushes a book on a table. 2. A person lands on a trampoline and slows Interactions Chart Child, car The car speeds up from rest when it is pushed. The car s INTERACTIONS AND ENERGY 2 MECHANICAL INTERACTIONS AND ENERGY PRACTICES ANSWERS 3. A box of cookies slows down as it slides across the table. 4. A kayak slows down after the kayaker stops paddling. Unit 2 Chapter 2 189 Activity 1 No Practice Activity 2 Practice 1. Example: A child pushes a toy car that was sitting on the floor. Interactions Chart Child, car The car speeds up from rest when it is pushed. The car s 1. A person pushes a book on a table. 2. A person lands on a trampoline and slows Person and book Person and trampoline Elastic Book speeds up from rest when it is pushed. Person slows Trampoline stretches. Book s Person s InterActions in Physical Science 361
CHAPTER 2 MECHANICAL INTERACTIONS AND ENERGY 12. and Drag Part 2 (In Practice Book) 1. When a stretchy object is no longer with anything, it goes back to its original relaxed shape, where it is no longer either stretched or compressed. 5. A bat is used to bunt a baseball. 2. Check to see if the student: a. described and/or sketched the interaction, b. identified the correct type for their interaction, c. listed at least two objects, d. described a change in speed, and e. showed that the change in corresponds to the change in speed. 6. A bicyclist stops pedaling and the bike slows 7. A person tosses an apple to a friend. 8. A player bumps a volleyball. 9. A jet zooms through the atmosphere. 10. A person pulls a wagon full of friends, making it go faster and faster. 3. A box of cookies slows down as it slides across the table. Box and table top The box of cookies slows Cookie s 11. A slingshot launches a beanbag. 4. A kayak slows down after the kayaker stops paddling. Kayak and water Drag Kayak slows Kayak s Water speeds 190 Water s InterActions in Physical Science up. increases 5. A bat is used to bunt a baseball. 6. A bicyclist stops pedaling and the bike slows 7. A person tosses an apple to a friend. Bat and ball Elastic Ball slows Bat jerks, ball deforms. Bike parts rubbing together, or Bike & rider and air Apple and hand, or Drag Bicycle slows Apple speeds up from rest. Ball s Bicycle s Air s increases Apple s 8. A player bumps a volleyball. 9. A jet zooms through the atmosphere. 10. A person pulls a wagon full of friends, making it go faster and faster. Arms and ball Jet and air Person and wagon Elastic Drag Ball slows down Jet slows air speeds up. (Students may not recognize this yet.) Wagon speeds up. Ball s Jet s air s Wagon s 11. A slingshot launches a beanbag. Slingshot and beanbag Elastic Beanbag speeds up Beanbag s 362 UNIT 2: INTERACTIONS AND ENERGY
Activity 3 Following the Energy Changes Activity 3: Following the Energy Changes Draw and complete an diagram for each situation below. An example diagram is done for you. Interaction Energy Diagram Example: A child pushes a toy car that was sitting on the floor. 1. A person tosses an apple to a friend. 2. A child slows down as he slides down a slide. 3. A kayak slows down after the kayaker stops paddling. Drag Child stored chemical Toy car INTERACTIONS AND ENERGY 2 MECHANICAL INTERACTIONS AND ENERGY Activity 3 Practice PRACTICES ANSWERS 4. A boy pulls a wagon full of friends, making it go faster 5. A puck slows down as it slides across ice. Unit 2 Chapter 2 191 Interaction Energy Diagram Interaction Energy Diagram Example: A child pushes a toy car that was sitting on the floor. Child Toy car 3. A kayak slows down after the kayaker stops paddling. Drag Kayak Water stored chemical 1. A person tosses an apple to a friend. Person Apple 4. A boy pulls a wagon full of friends, making it go faster Boy Slide and child 2. A child slows down as he slides down a slide. Child Slide and child 5. A puck slows down as it slides across ice. stored chemical Puck Ice and puck thermal thermal InterActions in Physical Science 363
CHAPTER 2 MECHANICAL INTERACTIONS AND ENERGY Interaction Energy Diagram (Questions 6-7) A bicyclist quits pedaling and bike slows down due to both a drag and friction interaction occurring at the same time. (Questions 6 7) A bicyclist quits pedaling and the bike slows down due to both a drag and friction interaction occurring at the same time. 6. Drag Bike and rider Air Interaction Energy Diagram (Questions 6 7) A bicyclist quits pedaling and the bike slows down due to both a drag and friction interaction occurring at the same time. 6. Drag You will need to draw two diagrams, one for each of the interactions. 7. (between the rubbing parts in the wheels) Bike Rubbing wheel parts thermal You will need to draw two diagrams, one for each of the interactions. 7. (between the rubbing parts in the wheels) Activity 4 Practice 1. bow decreases in arrow increases in 2. No, because for an elastic interaction the objects must be in contact with each other. Once the arrow leaves the bow they are no longer in contact. 3. Drag Interaction arrow air 192 InterActions in Physical Science Activity 4: s (Questions 1-3) An archer is shooting at a target to practice for a competition. She launches an arrow from her bow. 1. Draw an diagram for this interaction, showing the kind of interaction and the changes in. 2. Does the elastic interaction continue after the arrow has left the bow? Why or why not? 3. What does the arrow interact with after leaving the bow? Draw an diagram for this interaction. (Questions 4-6) A soccer player kicks a soccer ball to try to score a goal and just misses! The ball hits the metal pole on the side of the goal and rebounds backward. These four sketches show the ball hitting the pole, then bouncing off backwards and rolling on the grass (before the goalie scoops it up!) 4. Draw an diagram that describes what happens to the as the ball comes to a stop against the pole. 5. Draw an diagram that describes the ball rebounding off the pole. 6. Does the ball s interaction with the pole continue after they are no longer touching? How do you know? 4. decreases in soccer ball decreases in increases in soccer ball increases in (The metal pole can also be considered a receiver, since it will also compress very slightly and store elastic. However, since the pole is so hard compared to the soccer ball and its compression is not visible, it is not usually included in an diagram. 5. soccer ball decreases in soccer ball increases in 6. No, because for an elastic interaction the objects must be in contact with each other. Once the ball leaves the pole they are no longer in contact. Part 2 1. If the amount the spring is compressed changes, then what happens to the distance the car travels? 2. I think that if the amount the spring is compressed increases, then the distance the car travels will increase. because the more the spring is compressed, the more stored it will be able to transfer to the car. 3. The RV could be measured by using a meter stick and measuring the distance the car travels from the uncompressed spring position. 364 UNIT 2: INTERACTIONS AND ENERGY
Activity 5 Intreractions and Energy Transfer Activity 5: Interactions and Energy Transfer Multiple Choice Practice (Questions 1-2) Jerry and Hugh go to the bumper car arena at a nearby amusement park. At an opportune moment, Jerry bumps his car into his friend Hugh s car, which was not moving before the bump. The bump gives Hugh and his car a jolt, and Jerry s car slows 1. As Jerry s bumper car hits Hugh s car, what kind of interaction occurs? a) applied b) elastic c) friction d) drag e) magnetic 2. When Jerry s car bumps into Hugh s car, how does the change in the source? a) decreases in thermal b) decreases in stored chemical c) decreases in d) decreases e) increases (Questions 3-4) A boy pulls a skateboarder to help him speed up. 3. How does the change in the source? a) decreases Boy pulling b) decreases in thermal c) decreases in stored chemical d) decreases in e) no change Question 3 INTERACTIONS AND ENERGY Skateboarder & skateboard Question 4 2 MECHANICAL INTERACTIONS AND ENERGY 8. Spring Activity 5 Practice 1. (b) elastic interaction 2. (d) decreases 3. (c) decreases in stored chemical 4. (a) increases 5. (e) table and book (receivers) 6. (b) increases in thermal Part 2 (In Practice Book) 1. (a) water (receiver) Toy Car 2. (d) increases PRACTICES ANSWERS 4. How does the change in the receiver? a) increases b) increases in thermal c) increases in stored chemical d) increases in e) no change Unit 2 Chapter 2 193 4. 5. Variable Surface roughness Spring Strength Object s weight (RV) Distance Object Moves Trial 1 Trial 2 Trial 3 Trial 4 Table 1: Control Variables How it will be controlled Don t change the rubbing surface Don t change the spring Don t change the object s weight (e.g. don t put anything on it.) Table 2: Distance Object Moves Versus Distance Rubber Band Is Stretched (MV) Distance Rubber Band Is Stretched Average 8 32 148 9 35 150 7 30 146 10 31 153 8.5 32 149 6. I conclude that as the amount the spring is compressed increases, then the object travels further because, as the amount the spring was compressed changed from halfway to completely compressed, the distance the toy car traveled increased from 39.5 cm to 67 cm. There is no overlap between the ranges of distance values when taking into account their best values and uncertainties, so this conclusion is valid. 7. My conclusion agrees with my hypothesis since I thought that as the spring's compression increased, the distance the car travels would increase. InterActions in Physical Science 365
CHAPTER 2 MECHANICAL INTERACTIONS AND ENERGY Activity 6 Practice 1. (analysis) There is an elastic interaction between the rubber band and the block. Rubber band (explanation) The block speeds up because is transferred to the block from the rubber band during this elastic interaction. The block increases in, and the rubber band decreases in. 2. (analysis) There is a drag interaction between the block and the air. Block Drag Interaction Block Air 194 Book InterActions in Physical Science (Questions 5-6) After leaving contact with the hand, a book slows down as it slides across a table. The following diagram shows that the source decreases. 5. In the diagram, what is the receiver? a) table b) book c) hand d) book and hand e) table and book Question 5 Question 6 Activity 6: Analyze, Explain, and Evaluate 6. How does the change in the receiver? a) increases b increases in thermal c) increases in stored chemical d) increases in e) no change Read the task, perform an analysis, and write an explanation for each situation described. Use the following outline from How to Write an Analysis and Explanation. Analysis: Identify the objects and their interaction. Draw an diagram showing the transfers and changes. Explanation: Use your analysis, and the science ideas you have developed or learned, to help you answer the question. Refer to earlier activities and to your Scientists Ideas sheets to review your science ideas. Write your explanation using complete sentences. Your explanation should be able to pass the evaluation using the How to Evaluate an Analysis and Explanation. (Questions 1-2) Lucas launches a tightly bound bean bag block along a table top using a rubber band launcher. 1. Task: Why does the block speed up as Lucas lets go of the rubber band? Analyze and explain. 2. Task: Why does the block slow down after leaving contact with the rubber band? Analyze and explain. (explanation) The block slows down because is transferred to the air from the block during this drag interaction. The block decreases, and the air increases in. 366 UNIT 2: INTERACTIONS AND ENERGY
Activity 7 Designing Investigations Part 1 Activity 7: Designing Investigations Part 1 For help on this practice, refer to How to Design and Conduct an Investigation. 1. Investigations begin by asking a question that can be answered by gathering evidence. The investigation question always investigates the relationship between two variables, the manipulated variable and the responding variable. a) What does manipulated variable mean? b) What does responding variable mean? 2. There is an example of a good investigation question in How to Design and Conduct an Investigation, asking about the relationship between water saltiness and freezing time. For each situation below, write a good investigation question. a) Your uncle is curious about what is the hottest time of the day. b) The candy shop wants to know what age group buys the most chocolate candy. c) The planning commission needs to know the busiest time of day at the intersection of Main Street and Fourth Avenue. d) NASA needs to know the least windy month in Florida so they can plan rocket launches. 3. In each of the investigation questions that you wrote for 2, circle the manipulated variable and underline the responding variable. 4. Why are the following not good investigation questions for the situations in 2? INTERACTIONS AND ENERGY 2 MECHANICAL INTERACTIONS AND ENERGY PRACTICES ANSWERS a) What happens to the temperature? b) Who buys candy? c) Is the intersection of Main Street and Fourth Avenue busy? d) What is a good month in Florida for launching rockets? 5. What is a hypothesis? 6. Suppose you are investigating this question: As the time of day changes, what happens to the temperature? Write your hypothesis and reasons. 7. In your answer to 2, circle your hypothesis and underline your reasons. Unit 2 Chapter 2 195 InterActions in Physical Science 367
CHAPTER 2 MECHANICAL INTERACTIONS AND ENERGY NOTES 368 UNIT 2: INTERACTIONS AND ENERGY
(Unit 2 Chapter 2) Scientists Consensus Ideas Unit 2 Chapter 2 Answer Keys 6. The Interaction Defining Characteristics of the Interaction 2. Students should have evidence from a set-up that they created in U2C2 Act 2. If you demonstrated this in U2C2 Act 2, they may also describe your demonstration as evidence. Types of Interactions and the Variables That Influence Them interaction 7. a) Students should have evidence from the teacher demonstration. The teacher s edition suggests sliding a block across a table; the block should have different surfaces glued to it. As the surface becomes rougher, the block slows down more quickly and slides a smaller distance across the table. This shows an increase in the friction interaction between the two objects. b) Evidence could be from rubbing hands across each other under two situations: pressed together lightly, and pressed together firmly. When rubbed across each other in the second case, the hands become warmer. Since the hands are warmer, the friction interaction is stronger. Drag Interaction 9. a) A marble dropped in thick shampoo falls more slowly than a marble dropped in water. The drag interaction is stronger for the thicker liquid. b) When waving a notebook through the air, more air is moved when waving the cover of the notebook against the air than when waving the spine of the notebook through the air. c) You feel more resistance from the air as you ride your bike faster (or stick a hand slightly outside of a car's window as the car goes faster it is not safe to stick your hand out very far.) Elastic Interaction 11. In the video, when the tennis ball strikes the racquet strings the ball slows down, the ball compresses and the strings stretch. The ball s decreases while the ball increases in and the strings also increase in. 12. a) In the experiment with the rubber band and the car, the more the rubber band was stretched, the farther the car was launched. b) When we pushed or pulled on the springs (or rubber bands, or ), it was more difficult to stretch or compress the stiffer springs. This indicates that the stretchiness (stiffness) of an object affects the elastic interaction. SCIENTISTS CONSENSUS IDEAS ANSWERS InterActions in Physical Science 369