Prepared exclusively for Richard Pokorny Transaction: 1929

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3 Dr. Birdley Teaches Science! Forces and Motion Featuring the Comic Strip Middle and High School Innovative Resources for the Science Classroom Written and Illustrated by Nevin Katz Incentive Publications, Inc. Nashville, Tennessee

4 About the Author Nevin Katz is a teacher and curriculum developer who lives in Amherst, Massachusetts with his wife Melissa and son Jeremy. Nevin majored in Biology at Swarthmore College and went on to earn his Master s in Education at the Harvard Graduate School of Education. He began developing curriculum as a student teacher in Roxbury, Massachusetts. Mr. Katz has been teaching science for over seven years, in grades 6 through 11. He currently teaches Environmental Science and Physical Science at Ludlow High School in Ludlow, Massachusetts. Nevin s journey with Dr. Birdley and the cast began in the summer of 2002, when he started authoring the cartoon and using it in his science classes. From there, he developed the cartoon strip, characters, and curriculum materials. After designing and implementing the materials, he decided to develop them further and organize them into a series of books. Cover by Geoffrey Brittingham Edited by Jill Norris Science Editors: K. Noel Freitas and Scott Norris ISBN All Rights Reserved. The Dr. Birdley comic strip and all characters depicted in the comic strips, Copyright 2007 by Nevin Katz. All rights reserved. The Dr. Birdley logo, Dr. Birdley TM, Jaykes TM, Dean Owelle TM, Professor Brockley TM, Gina Sparrow TM, and all prominent characters featured in this publication are trademarks of Nevin Katz. No part of this publication may be reproduced, stored in a retrieval system, or transmitted in any form or by any means (electronic, mechanical, photocopying, or otherwise) without written permission from Incentive Publications, with the exception below: Pages labeled with the statement Copyright 2008 by Incentive Publications are intended for reproduction within the owner s classes. Permission is hereby granted to the purchaser of one copy of Forces and Motion to reproduce these pages in sufficient quantities for meeting the purchaser s classroom needs only. Please include the copyright information at the bottom of each page on all copies PRINTED IN THE UNITED STATES OF AMERICA

5 Table of Contents Contents Objectives and Frameworks...2 Teacher s Guide...5 Unit 1: Speed, Distance, and Time...11 Unit 2: Velocity...19 Unit 3: Acceleration...29 Unit 4: Newton s Law of Gravitation...39 Unit 5: Newton s Laws of Motion...49 Unit 6: Force, Mass, and Acceleration...59 Unit 7: Motion in Two Dimensions...69 Unit 8: Disrupted Inertia...79 Answer Key

6 Educational Objectives Central Goals: To explain and illustrate concepts of velocity, acceleration, force, and gravity To apply these ideas to real-life situations and connect them to Newton s laws of motion and gravitation Chapter or Unit Primary Objective(s) Standards 1. Speed, Distance, and Time To calculate time, distance, and speed using mathematical formulas. To represent changes in position using distance-time graphs 1, 2 2. Velocity To understand velocity as speed combined with direction. To calculate velocity using vectors and distance-time graphs. 3. Acceleration To understand that acceleration can be a change in speed, direction, or both. 4. Newton s Law of Gravitation 5. Newton s Laws of Motion To calculate acceleration and final velocity of moving objects. To apply Newton s law of gravitation to planets and moons, as well as small everyday objects. To illustrate how gravitational force is calculated. To understand the major ideas behind Newton s Laws. To define force and explore the concept of net force. To introduce the concepts of inertia and action-reaction force pairs. To calculate force, mass, and acceleration using Newton s second law. 1, 2, 5 1, 5 10, Force, Mass, and Acceleration 7. Motion in Two Dimensions 8. Inertia and Friction To learn how to calculate force, mass, and acceleration. To understand how equal amounts of drag force and gravitational force result in terminal velocity. To distinguish between the horizontal and vertical components of an object in motion. To understand the independent nature of these two components. To describe and illustrate how gravity and air resistance affect projectile motion. To understand how the law of inertia is applied to moving objects in real life. To understand how frictional forces can interferre wtih inertia. 4, 6, 8 1, 5 3, 5 2

7 Relevant Frameworks Motion & Forces, Grade The motion of an object can be described by its position, direction of motion, and speed. 2. Motion can be measured and represented on a graph. 3. An object that is not being subjected to a force will continue to move at a constant speed and in a straight line. 4. If more than one force acts on an object along a straight line, then the forces will reinforce or cancel one another, depending on their direction and magnitude. 5. Unbalanced forces will cause changes in the speed or direction of an object s motion. Motion & Forces Standards, Grades Objects change their motion only when a net force is applied. 7. Laws of motion are used to calculate precisely the effects of forces on the motion of objects. 8. The magnitude of the change in motion can be calculated using the relationship F = ma, which is independent of the nature of the force. 9. Whenever one object exerts force on another, a force equal in magnitude and opposite in direction is exerted on the first object. 10. Gravitation is a universal force that each mass exerts on any other mass. 11. The strength of the gravitational attractive force between two masses is proportional to the masses and inversely proportional to the square of the distance between them. 3

8 Overview of Forces & Motion Source Cartoons The difficulty level ranges from easy (L1) to very challenging (L3). Cartoon Central Concepts Challenge Level Related Topics Rollerblades Representing speed on distance-time graphs L1 Scientific Method Data Analysis Velocity in Tennis Velocity and vectors L2 Projectile Motion Acceleration Vectors on a River Finding resultant velocity through vector addition L3 Pythagorean Theorem Camel Acceleration and deceleration L1 Velocity Science Sharks Calculating final velocity of a falling object L2 Acceleration Due to Gravity Birdley Meets Newton Gravitational Force Owelle Meets Newton Newton s Law of Gravitation L1 Newton s Life The equation for gravitational force. L3 Scientific Notation Newton s Three Laws Of Motion L2 The Newton Balance Tug-of-war Balanced and unbalanced forces L1 Friction Baseball Horizontal and vertical components of a baseball s trajectory L2 Acceleration Due to Gravity Hang Time Horizontal and vertical components of jumping. L2 Acceleration Due to Gravity Initial and Final Velocity Forces in Hockey Terminal Velocity Force, mass, and acceleration L2 Friction Drag force, gravity, and terminal velocity L2 Balanced Forces Net Force Force and Acceleration Inertia The inertia of objects in motion L2 Projectile Motion Friction in Golf The effect of friction on inertia L1 Types of Friction 4

9 Unit 1: Speed, Distance, and Time Contents Source Cartoon: Speed on a Graph 12 Cartoon Profile 13 Background 14 Study Questions 15 Visual Exercise 16 Vocabulary Build-up 17 Quiz 18 11

10 distance (km) Copyright 2007 by Nevin Katz time (minutes) 12

11 SPEED ON A GRAPH Distance, Time, Speed Objectives 1. To define speed as the amount of distance an object travels over time 2. To show how speed is represented as the slope of a line on a distance-time graph 3. To illustrate how distance-time graphs indicate speed, as well as changes in speed Synopsis Owelle and Phyll begin by explaining the definition of speed. They compare the speeds of two model cars using a distance-time graph. In the next scene, Dr. Birdley is jogging, while Clarissa is rollerblading. Owelle then presents a distance-time graph that illustrates changes in their speed during the workout. Main Ideas 1. Speed is the amount of distance an object travels over time 2. On a distance-time graph, the speed of an object is represented by the steepness of the slope. 3. Gradual slopes indicate low speed. 4. Steep slopes indicate high speed. 5. A flat line on a distance-time graph indicates a speed of zero. Vocabulary distance time speed y-axis x-axis slope Characters Dean Owelle, Phyll, Dr. Birdley, Clarissa Teacher s Notes Help students make the connection between the panels on Clarissa s movement and the graph. The lines on the graph are in sync with the panels. A problem-solving strategy for calculating slope is featured in the background section. 13 Questions for Discussion Before Reading: 1. How do you define speed? 2. What units are used to measure distance? Time? 3. What different types of graphs might be used to show data? After Reading: 1. How does Dean Owelle define speed? 2. What is a slope? 3. Look at the panel where Clarissa speeds up. What do you notice about the slope of her line in the graph at that point?

12 SPEED, DISTANCE, AND TIME NAME: CLASS: DATE: BACKGROUND: SOLVING FOR SPEED The following procedure can be used to find the speed of a moving object. A train travels a distance (d) of 500 meters in a time (t) of 50 seconds. What is the speed (s)? 1. Write out the formula you are using. s = d / t. 2. Write down all your known quantities. d = 500 m t = 50 s. 3. Substitute these quantities into the equation. 4. Solve. s = 500 m / 50s s = 10 m/s Directions: Solve the following problem to the best of your ability. A dinosaur walks 600 meters in 30 seconds. What is its speed? FINDING THE SLOPE OF A LINE You can also find speed by finding the slope of a line on a graph. Here is how you do it: Pick two points with coordinates (x 1, y 1 ) and (x 2, y 2 ) For example, points (2, 4) and (4, 8) on the graph to the right. Then, plug the coordinates into the equation below; slope (m) = rise = (y 2-y 1 ) = (8-4) 4 = run (x 2 -x 1 ) (4-2) 2 This method works for any other two points on this graph. = 2 meters/second Distance (meters) Distance-Time Graph (4, 8) (2, 4) Time (seconds) 14

13 SPEED ON A GRAPH NAME: CLASS: DATE: STUDY QUESTIONS Directions: Answer the following questions to the best of your ability. 1. Look at the second panel in Speed on a Graph. How does the graph tell you that car B is moving faster than car A? 2. According to the graph in the last panel, what is Owen s speed (in meters per minute) over the first 15 minutes? How far does he travel? 3. According to the graph, what is Clarissa s speed (in meters per minute) between 15 and 25 minutes? 4. Do Owen and Clarissa reach their starting point at 50 minutes? How do you know? 5. Owelle and Birdley run a road race, and their performance is recorded on a distance-time graph. The slope of Birdley s line is steeper than Owelle s. What does this mean? 15

14 DISTANCE-TIME GRAPH NAME: CLASS: DATE: WORKOUT INFO A. At this point, Clarissa stops. B. Clarissa goes from a faster speed to a slower speed. C. Here, Clarissa goes from a slow speed to a faster speed. D. Clarissa changes direction a second time. E. Clarissa starts moving again, this time in the reverse direction. F. Clarissa travels six meters at a steady speed. Distance Traveled by Clarissa Over Time Distance (in meters) Time (seconds) 6. What is the slope of the line in the first three seconds? 7. What is Clarissa s speed between three and eight seconds? How do you know? 8. When does Clarissa reverse direction while maintaining a constant speed? 16

15 SPEED, DISTANCE, AND TIME NAME: CLASS: DATE: VOCABULARY BUILD-UP Directions: Read the definition and sample sentence. Then, write your own sample sentence and draw a cartoon that illustrates speed. Definition: Speed is the amount of distance covered per unit time. Sample sentence: Clarissa Birdley s speed is the fastest in the middle of her workout, when she is traveling at a speed of 15 m/s. Give a sample sentence of your own that conveys the meaning of speed. Draw a cartoon that illustrates the meaning of speed. Use words and pictures to convey its definition. Useful elements include: word balloons and narration panels fast and slow objects characters, places, objects someone measuring the speed of an object numbers and formulas tools used to measure speed 17

16 Name: Class: Date: Unit 1 Quiz: Speed Directions: Birdley is running on a soccer field to warm up for a race. Examine the graph of the distance he travels below. Then, answer the related questions to the best of your ability. Distance (in meters) a Birdley moves in the same direction and increases his speed at point e point b point c point d 2. Birdley reverses direction at the following points a and c e and d b and d b and f Distance Traveled by Birdley Over Time b c Time (seconds) d 4. Birdley is not moving between points a and b b and c c and d d and e 5. Birdley heads towards the starting location between the points a and b b and c c and d d and e e f 3. From point b to point c, Birdley s speed (shown by the slope of the line) is equal to 0.4 m/s 2.5 m/s 10 m/s 3.5 m/s Birdley stays in the same direction and slows down at point b point d point e point f

17 Unit 2: Velocity Contents Source Cartoon: Tennis & Velocity 20 Source Cartoon: Vectors on a River 21 Cartoon Profiles (2) 22 Study Questions (2) 24 Background 26 Visual Exercise 27 Vocabulary Build-up 28 19

18 Copyright 2007 by Nevin Katz 20

19 Copyright 2007 by Nevin Katz 21

20 TENNIS & VELOCITY Velocity and Vectors Objectives 1. To define and give examples of velocity. 2. To illustrate how velocity is represented with vectors 3. To explain why velocity changes along a curved paths. Synopsis Birdley and Norman are playing Jaykes and Birdley s dad in a game of tennis doubles. After a couple of questions by Norman, Birdley begins explaining the velocity of the tennis ball. As Birdley finishes his explanations, Norman wins the point with an overhead smash. Main Ideas 1. Velocity describes the speed and direction of an object. 2. Velocity vectors can be represented by arrows, which have both direction and magnitude. 3. If an object follows a curved path, velocity is constantly changing because the object s direction is changing. Vocabulary velocity vectors magnitude speed direction Characters Dr. Birdley, Jaykes, Norman, Birdley s dad Teacher s Notes Draw the multiple vectors of a curved path to show how it is different from a straight path. One example is the vector breakdown of this ball s trajectory: Questions for Discussion Before Reading: 1. In tennis, how do you control the speed and direction of the ball? 2. How would you control the speed and direction of a ball in another sport? 3. What do you already know about speed? After Reading: 1. What was the direction of Norman s ball? 2. How could vectors be used to represent the curved path of a tennis ball? 3. How is velocity different from speed? 22

21 VECTORS ON A RIVER Vector Addition Objectives 1. To illustrate how a problem involving two components to velocity can be solved using vector addition. 2. To illustrate the steps of the Pythagorean Theorem. Synopsis Dr. Birdley and Dean Owelle are paddling their canoe along a river. As Birdley begins to philosophize, Owelle notices that they are headed toward the waterfall. After they turn the boat toward the riverbank, Birdley attempts to calculate the resultant velocity of the boat through vector addition. The solution to the problem is below and in this unit s background section. Main Ideas 1. Vectors represent speed and direction. 2. To find the resultant velocity of a boat on a river, the velocity of the boat itself and the velocity of the river flow must be taken into account. 3. Resultant velocity can be found using vector addition. 4. For problems involving two perpendicular velocities, resultant velocity can be found using the Pythagorean Theorem where a, b, and c are three sides of a right triangle and c is the unknown velocity: b = 3 m/s a 2 + b 2 = c = c 2 c =? = 25 = c 2 a = 4 m/s Vocabulary c = c 2 = 25 = 5 vectors velocity vector addition hypotenuse Pythagorean Theorem Questions for Discussion Before Reading: 1. If you are traveling by canoe, why is it easier to go with the flow of a river? 2. What happens if you go against the flow? Why? 3. If you are going with the flow of a river, what would happen to the boat if you paddled directly toward a riverbank? After Reading: 1. Did Birdley finish the problem by the time Owelle jumped off the boat? 2. What steps are left for solving the problem? Go through them? Characters Dr. Birdley, Dean Owelle 23

22 TENNIS & VELOCITY NAME: CLASS: DATE: STUDY QUESTIONS Directions: Answer the following questions to the best of your ability. 1. Suppose a tennis ball is flying through the air at 70 mph. Does this statement describe the tennis ball s velocity? Why or why not? 2. Write a statement that describes the velocity of a moving object. 3. Suppose a roller coaster car is moving in a curved path at a steady speed of 60 mph. Is it changing velocity? How do you know? 4. List three events in a tennis game that would change the velocity of the ball. 5. Suppose Norman s backhand sends the ball flying with a starting velocity of 75 mph east. Could the wind affect the velocity of the ball? Explain. 24

23 VECTORS ON A RIVER NAME: CLASS: DATE: STUDY QUESTIONS Directions: Answer the following questions to the best of your ability. 1. In what direction is the boat headed at the beginning of the comic? What causes the boat to change its velocity? 2. Describe the general direction of the boat after Birdley and Owelle steer it toward the riverbank. Use the compass shown in the comic. 3. As Birdley and Owelle paddle toward the riverbank, what two factors affect the boat s velocity? 4. Why does Birdley use the Pythagorean Theorem? 5. What is the boat s resultant velocity? (Hint: Use the Pythagorean Theorem to find the length of the triangle s longest side.) 25

24 VECTOR ADDITION NAME: CLASS: DATE: BACKGROUND: PYTHAGOREAN THEOREM AND VECTORS If a vehicle s velocity has two perpendicular components, you can use the Pythagorean Theorem to find the resultant velocity. This procedure shows you how. 1. Draw the two perpendicular velocities as vectors, oriented head to tail. 2. Draw the resultant vector so that you form a right triangle. 4 m/s a = 4 m/s 3 m/s b = 3 m/s c =? 3. Set up the pythagorean equation. 4. Plug in your known quantities. a 2 + b 2 = c = c 2 5. Multiply exponents = c 2 6. Add. 7. Find the square root of c. 25 = c 2 c = c 2 = 25 = 5 m/s northeast Directions: Solve the following problem to the best of your ability. 1. A boat is sailing north at 24 m/s. The river is flowing east and 18 m/s. Draw a diagram and use the Pythagorean Theorem to find final velocity. 26

25 VECTOR ADDITION NAME: CLASS: DATE: Pythagorean Theorem: a = 4 m/s b = 3 m/s c =? a 2 + b 2 = c = c = 25 = c 2 c = c 2 = 100 = 10 boat: 40 m/s, north river: 30 m/s, east river: 9 m/s, northwest boat: 12 m/s, northeast 1. Resultant velocity of boat: 2. Resultant velocity of boat: river: 16 m/s, north river: 20 m/s, west boat: 15 m/s, north boat: 12 m/s, east 3. Resultant velocity of boat: 4. Resultant velocity of boat: 27

26 VELOCITY AND VECTORS NAME: CLASS: DATE: VOCABULARY BUILD-UP Directions: Read the definition and sample sentence. Then, write your own sample sentence and draw a cartoon that illustrates velocity. Definition: Velocity is a quantity that describes speed and direction. Sample sentence: The velocity of the golf ball is 10 m/s northeast. 10 m/s, NE Give a sample sentence of your own that conveys the meaning of velocity. Draw a cartoon that illustrates the meaning of velocity. Include some of thse elements: word balloons and narration panels characters, places, objects, numbers, vectors, and formulas 28

27 Unit 3: Acceleration Contents Source Cartoon: The Camel 30 Source Cartoon: Science Sharks 31 Cartoon Profiles (2) 32 Study Questions (2) 34 Background 36 Visual Exercise 37 Vocabulary Build-up 38 Quiz 39 29

28 Copyright 2007 by Nevin Katz 30

29 Copyright 2007 by Nevin Katz 31

30 THE CAMEL Acceleration Objectives 1. To define acceleration in relation to velocity. 2. To illustrate the circumstances under which an object accelerates. Synopsis As Birdley rides a camel through the desert, he teaches a lesson on acceleration. The camel accelerates in various ways to illustrate this concept. Main Ideas 1. Acceleration always involves a change in velocity over time. 2. When an object s speed increases, it covers more distance per unit time with every passing second. 3. Acceleration can involve a change in speed, direction, or both. 4. When an object decelerates, it slows down. Vocabulary acceleration velocity speed direction time distance Characters Dr. Birdley, desert cop, camels Teacher s Notes The comic and study questions set you up to introduce this equation for finding acceleration: a = acceleration v i = initial velocity v f = v i + (a x t) t = time v f = final velocity Questions for Discussion Before Reading: 1. What does a car do when it accelerates? 2. Does a rollercoaster accelerate? If so, when? 3. How could you change velocity when you are walking? After Reading: 1. What does it mean to decelerate? 2. Look at the third (long) panel in the comic. What happens over time to the amount of distance the camel covers per second? Why? 3. Based on the comic, what do you think it means to decelerate? 32

31 SCIENCE SHARKS Acceleration and Gravity Objectives 1. To provide an example of acceleration due to gravity. 2. To illustrate the steps for solving for final velocity using time, acceleration, and initial velocity. Synopsis From the deck of a ship, Dr. Birdley drops a rock into the water. Two of the science sharks use the information, gather information about the drop, and calculate the rock s final velocity just before it hits the water. Main Ideas 1. Before solving a problem, write out the formula you are using. In this case, v f = v i + (a x t). 2. Use the information in the situation to write down all your known quantities. Include units. In this case, you have: v i = initialy velocity = 0 m/s t = time = 2 s. a = acceleration = 9.8 m/s 2 3. Substitute these quantities into the equation and you have: v f = 0 m/s + (9.8 m/s 2 x 2 s) 4. Solve. v f = 19.6 m/s 5. If an object is dropped, it accelerates due to gravity. The more time it has to fall, the greater its final velocity is just before impact. Vocabulary acceleration time initial velocity equation variable final velocity knowns unknowns gravity Characters Dr. Birdley and the Science Sharks 33 Questions for Discussion Before Reading: 1. What happens to the speed of a falling object? Why? 2. What do you need to know in order to find an object s acceleration? Final velocity? 3. What determines how long it takes for something to fall? 4. What determines the speed of a falling object? After Reading: 1. Suppose Birdley drops the rock from a lower point. How would this affect the rock s final velocity? 2. How did the sharks calculate the rock s final velocity?

32 THE CAMEL NAME: CLASS: DATE: STUDY QUESTIONS Directions: Answer the following questions to the best of your ability. 1. How does acceleration relate to velocity? 2. Suppose a camel heading north remains at the same speed but then changes its direction towards the east. Does it accelerate? Why or why not? 3. A camel with an initial velocity of 10 m/s starts to accelerate at 5 m/s 2 for five seconds. What is the camel s final velocity? Show your work. 4. A camel speeds up, maintains the same speed for ten seconds, and then gets tired and slows down. When is the camel decelerating? Why? 5. How does Dr. Birdley s camel end up speeding? Use the term accelerate or acceleration in your answer. 34

33 If SCIENCE SHARKS NAME: CLASS: DATE: STUDY QUESTIONS Directions: Answer the following questions to the best of your ability. 1. What are the sharks trying to find? What information did the sharks gather through observation? 2. What information did the sharks write down before solving the problem? What equation did they use? 3. Suppose Birdley were to attach a parachute to the rock he drops. How would this affect the rock s final velocity? Why? 4. Another rock is dropped from a higher point and falls for 5 seconds before hitting the ground. Assuming acceleration due to gravity is 9.8 m/s 2, what is the rock s final velocity the instant before it hits the ground? 5. How will the rock accelerate or decelerate when it hits the water? Why? 35

34 ACCELERATION NAME: CLASS: DATE: BACKGROUND: PROCEDURE FOR FINDING FINAL VELOCITY Use the following procedure to solve for the final velocity of a moving object that is accelerating. v f = final velocity, v i = initial velocity, a = acceleration, and t = time. 1. Write out the formula you are using. v f = v i + (a x t). 2. Write down all your known quantities. 3. Substitute these quantities into the equation. 4. Solve. v i = 0 m/s t = 2 s. a = 9.8 m/s 2 v f = 0 m/s + (9.8 m/s 2 x 2 s) v f = 19.6 m/s Directions: Solve the following problems to the best of your ability. 1. A resting object is dropped, and falls for six seconds before hitting the ground. Assuming that acceleration due to gravity is 9.8 m/s 2, find its final velocity before impact. 2. A car initially going at 30 m/s accelerates by 5 m/s 2. Find the car s velocity after it has accelerated for seven seconds. 36

35 ACCELERATION EQUATIONS NAME: CLASS: DATE:

36 Name: Class: Date: Unit 3 Quiz: Acceleration Directions: This quiz tests your knowledge of the chapter s cartoon, background article, and visual exercises. Answer the following questions to the best of your ability. 1. Acceleration always involves a change in speed velocity direction gravity 2. If a truck decelerates, it always speeds up maintains a constant speed slows down comes to a complete stop 3. A car traveling at a speed of 30 m/s changes speed to 50 m/s over four seconds. What is the car s acceleration? 80 m/s 2 20 m/s m/s 2 5 m/s 2 4. A rock is dropped from rest and falls for four seconds before hitting the ground. Assuming acceleration due to gravity is 9.8 m/s 2, what is the rock s final velocity the instant before it hits the ground? 39.2 m/s m/s m/s m/s 2 5. A box is falling with a downward velocity of 10 m/s. It falls for two more seconds before hitting the water. Assuming acceleration due to gravity is 9.8 m/s 2, what is the box s final velocity before hitting the water? 19.8 m/s m/s m/s m/s 2 6. A person walking at 2 m/s changes direction but still continues walking at the same speed. Is this person accelerating? Why or why not? 7. A cyclist starting from rest accelerates at a rate of 6 m/s 2 until she reaches 30 m/s. How long does it take her to accelerate? (Hint: re-arrrange your equation for acceleration so that you solve for time.) 38

37 Unit 5: Newton s Laws of Motion Contents Source Cartoon: Owelle meets Newton 50 Source Cartoon: Tug of War 51 Cartoon Profiles (2) 52 Study Questions (2) 54 Mini-Comic: Action-Reaction Pairs 56 Visual Exercise 57 Vocabulary Build-up 58 49

38 Copyright 2007 by Nevin Katz 50

39 Copyright 2007 by Nevin Katz 51

40 OWELLE MEETS NEWTON Laws of Motion Objectives 1. To introduce Newton s three laws of motion. 2. To introduce the Newton balance, which measures force in Newtons. Synopsis After bringing Newton to the present, Birdley introduces him to Dean Owelle, who doubts the great scientist s true identity. Newton proves his identity by explaining his three laws of motion. As he explains them, Jaykes provides examples of the three laws using his lab equipment. Main Ideas 1. An object at rest tends to stay at rest, and an object in motion tends to stay in motion, unless acted upon by an outside force. 2. The force exerted on an object is equal to its mass multiplied by its acceleration. (F = ma) 3. Every action results in an equal and opposite reaction. Vocabulary force action reaction Newton (N) Newton meter inertia mass acceleration Characters Dr. Birdley, Sir Isaac Newton, Jaykes, Dean Owelle, Norman Teacher s Note The comic sets you up to introduce the term inertia. Prior to introducing the comic, it helps for students to be familiar with air resistance and friction, which also disrupt the ball s inertia (referred to in study question #2, p. 54). Questions for Discussion Before Reading: 1. What do you know so far about Sir Isaac Newton? 2. What is a force? 3. What do you already know about gravity? After Reading: 1. What were Newton s three laws? 2. If you were Owelle, would you be convinced that the guy is Newton? Why or why not? 3. What does Norman do to the ball s inertia? 52

41 TUG OF WAR Net Force Objectives 1. To introduce the Newton as the unit for force. 2. To compare and contrast balanced and unbalanced forces. 3. To introduce the concept of net force. Synopsis Dr. Birdley uses a tug-of-war match to explain the concept of balanced forces. Norman pulls the rope on one end, creating a net force in his direction. Don advises two students to restore balance to the tug-of-war match. Main Ideas 1. Force is measured in Newtons. 2. When two forces are equal and opposite in direction, the net force is zero and there is no acceleration. 3. In the tug-of-war match, the two opposing forces create tension at the center of the rope. 4. If a force in one direction is greater than the force in the opposite direction, then there is a net force, resulting in movement. Vocabulary net force Newton balanced unbalanced Characters Dr. Birdley, Dean Owelle, Jaykes, Gina, Lark, Norman, Don, Anthony, Christina Teacher s Notes Question #3 involves the use of friction, so it would be useful to touch on friction with your students before using the comic. In this case, Jaykes and Owelle dig their feet into the ground to create friction that opposes their forward motion. Questions for Discussion Before Reading: 1. What happens in a tug-of-war match? 2. How does someone win a tug-of-war match? After Reading: 1. Why did Jaykes and Owelle start moving? 2. What could the students do to restore balance to the tug-of-war match? 3. How did net force change during the comic? 53

42 OWELLE MEETS NEWTON NAME: CLASS: DATE: STUDY QUESTIONS Directions: Answer the following questions to the best of your ability. 1. Based on Norman s comment, how would you define inertia? 2. Suppose the surface is not totally smooth. What additional outside force would be affecting the ball s motion? How would its motion be affected? 3. How is Jaykes measuring the amount of force he uses to pull the weight? What are the two other properties that relate to force? 4. How does the Newton meter demonstrate the law of action and reaction? 5. If Jaykes causes a 0.5 kg weight to accelerate by 5 m/s 2, what force is Jaykes using to pull the weight? Assume the weight is on a frictionless surface. Use the equation he s thinking of. 54

43 If TUG-OF-WAR NAME: CLASS: DATE: STUDY QUESTIONS Directions: Answer the following questions to the best of your ability. 1. When do two forces result in no motion? 2. In the comic, what causes the forces to become imbalanced? What is the net force in this case? 3. What are Jaykes and Owelle doing to resist being pulled any further? What principle of physics are they using? 4. How could Anthony and Christine restore balance to the tug-of-war match? 5. If Gina and Owelle were to compete by themselves in a tug-of-war match and use the same force as in this comic, who would win? What would be the net force? 55

44 Newton s Law states that every action results in an equal and opposite reaction. For example, as Dr. Birdley s weight pushes down on a bridge, a sturdy bridge will push back up on Dr. Birdley. This can be illustrated using a force pair diagram, where arrows represent the directions of the forces at work (see above). After the bridge breaks, the force pairs change. The earth is pulling down on Owelle, while Owelle is pulling up on the earth (see below.) Action-reaction pairs can also be horizontal. Here, as Dr. Birdley pushes on the cabinet, the cabinet pushes back on him. Draw the arrows here to represent the pair of forces at work. Copyright 2007 by Nevin Katz 56

45 ACTION / REACTION PAIRS NAME: CLASS: DATE: 57

46 FORCE NAME: CLASS: DATE: VOCABULARY BUILD-UP Directions: Read the definition and sample sentence. Then, write your own sample sentence and draw a cartoon that illustrates velocity. Definition: A force is defined as a push or a pull on an object. Sample sentence: Norman pulled the rope with a force of 30 Newtons. Give a sample sentence of your own that conveys the meaning of force. Draw a cartoon that illustrates the meaning of force. Useful elements include: word balloons and narration panels characters, places, objects, numbers and formulas arrows with labels that indicate specific amounts of force (ex. F = 40 N) 58

47 Unit 6: Force, Mass, and Acceleration Source Cartoon: Forces in Hockey 60 Source Cartoon: Terminal Velocity 61 Cartoon Profiles (2) 62 Study Questions (2) 64 Visual Exercise 66 Quiz 67 Reference Sheet: Key Formulas 68 59

48 Copyright 2007 by Nevin Katz 60

49 t = 0 v = 0 m/s Copyright 2007 by Nevin Katz 61

50 FORCES IN HOCKEY Newton s Second Law Objectives 1. To illustrate how the equation F = ma applies to hockey. 2. To show how to rearrange the variables in the equation to solve for acceleration. 3. To show the relationship between force and acceleration. 4. To show how mass and acceleration are related. 5. To pair equations with action sequences that students can readily understand. Synopsis While coaching hockey practice, Dr. Birdley explains how Newton s second law (F = m x a) applies to ice hockey. Main Ideas 1. Force is equal to the mass of an object multiplied by its acceleration (F = m x a). 2. Acceleration is equal to the force exerted on an object divided by mass. (a = F/m). 3. In other words, the greater an object s mass, the less it will accelerate given an equal amount of force. 4. Increasing the amount of force you use on an object will increase the object s acceleration. Vocabulary force acceleration mass units kilograms Newtons Characters Dr. Birdley, Shelly, Neil, Anthony Teacher s Note The acceleration of the large puck in the final panel is 3 m/s Questions for Discussion Before Reading: 1. What do we know so far about force? mass? acceleration? 2. If you slide an object across your desk, how can you control how far it goes? How fast it goes? After Reading: 1. How are the characters able to control the speed of the hockey puck? 2. What is the large hockey puck s acceleration? 3. Why does this hockey puck accelerate less?

51 TERMINAL VELOCITY Gravity and Net Force Objectives 1. To connect gravity to the formula a = F/m. 2. To discuss the connection between air resistance and terminal velocity. Synopsis As Dr. Birdley goes skydiving, he explains how he reaches terminal velocity. He opens his parachute to slow his fall, but gets stuck in a tree on the way down. Main Ideas 1. Before reaching terminal velocity, Birdley accelerates due to gravity. 2. The other force at work is drag force, which is caused by air resistance. 3. As Birdley speeds up, drag force increases. This is because drag force is proportional to the square of an object s speed. 4. Birdley reaches terminal velocity when the downward force of gravity is equal to the upward force of drag. 5. At this point, drag force cancels the force of gravity, resulting in zero downward acceleration. In terms of Newton s formula, (a = F/m), here is what happens to net force: F F g - F d a = m = m = 0 where F g = force of gravity and F d = force of drag 6. Because of its shape, the parachute increases the amount of drag Birdley experiences and lowers Birdley s terminal velocity dramatically. Vocabulary terminal velocity gravity acceleration air resistance drag free fall Characters Dr. Birdley and Detective Eggs Benedict Questions for Discussion Before Reading: 1. Suppose you are skydiving. What happens to your velocity / speed as you fall? 2. How do parachutes work? 3. How do you think air resistance affects your fall? After Reading: 1. When does terminal velocity happen in the comic? 2. Why does Dr. Birdley s parachute slow his fall? 3. Why does Dr. Birdley stop accelerating? 63

52 FORCES IN HOCKEY NAME: CLASS: DATE: STUDY QUESTIONS Directions: Answer the following questions to the best of your ability. 1. Translate the equation F = ma into a sentence. 2. How does the amount of force you use affect the acceleration of a hockey puck? 3. Suppose you push two boxes with a force of 5 N. One box has a mass of 1 kg and one box has a mass of 2 kg. Which box will speed up faster? Why? 4. After being hit with a hockey stick, a.20 kg puck accelerates at 50 m/s 2. What is the amount of force exerted on the puck? 5. Let s say 25 N of force are exerted on the.25 kg puck. What is the puck s acceleration? 64

53 TERMINAL VELOCITY NAME: CLASS: DATE: STUDY QUESTIONS Directions: Answer the following questions to the best of your ability. 1. What happens to Dr. Birdley s velocity over the first several seconds? Why? 2. What force does force of drag oppose? What happens to force of drag as velocity increases? 3. Compare force of drag and gravitational force once Birdley reaches terminal velocity. What is the resulting net force? 4. What happens to Birdley s acceleration at terminal velocity? Why? (Hint: what is the net force that results from drag opposing gravity? How are force and acceleration related?) 5. Does the parachute increase or decrease Dr. Birdley s terminal velocity? How? Explain your answer. 65

54 FORCE, MASS, AND ACCELERATION NAME: CLASS: DATE: 66

55 Name: Class: Date: Unit 6 Quiz: Newton s Laws of Motion Directions: This quiz tests your knowledge of the cartoons, mini-comics, and visual exercises from units 5 and 6. Answer the following questions to the best of your ability. 1. A.15 kg hockey puck, starting at rest, is pushed so that it accelerates by 50 m/s 2. What is the force exerted on the puck? N 330 N 7.5 N N 2. If an object is in motion, and there are no outside forces acting on it, the object s speed will eventually reach 0 m/s remain the same increase over time decrease over time 3. You push down on a table with your hands, and the table does not break. The table is not pushing back at all pushing down in the same direction pushing sideways pushing back up on your hands with equal force 4. At terminal velocity, a skydiver stops accelerating because the acting on her becomes to zero. gravitational force force of drag net force the mass 5. If only two equal yet opposing forces are pushing on an object, the net force is always zero positive negative constantly changing 6. An object is in inertia if it has no net forces acting on it. gets pushed or pulled is accelerating is falling 7. A person is standing on a bridge. Identify the two opposing forces at work in the space below. Then, draw a diagram of the situation. Use arrows to illustrate the two opposing forces. Action Force: Diagram: Reaction Force: 67

56 FORCES & MOTION NAME: CLASS: DATE: Reference Sheet: Key Formulas Directions: In each box, write the correct formula that is used to find the property that is listed. Speed, Time, and Distance Accleration, Time, and Velocity Force, Mass, Acceleration, and Gravitation Speed (s) acceleration (a) Force (F) Time (t) time (t) acceleration (a) distance (d) final velocity (v f ) mass (m): slope (m) m = rise / run deceleration (d) Gravitational Force (F g ) *This slope formula would use two points on a line graph, with coordinates (x 1, y 1 ) and (x 2, y 2 ). 68

57 Unit 8: Disrupted Inertia Source Cartoon: Inertia 80 Source Cartoon: Friction in Golf 81 Cartoon Profiles (2) 82 Study Questions (2) 84 Visual Exercise 86 Mini-Comic 87 79

58 Copyright 2007 by Nevin Katz 80

59 IT S INERTIA Laws of Motion Objectives 1. To show that an object is in inertia if no forces are acting on it. 2. To illustrate that an object in inertia could still be in motion. 3. To practice breaking up an object s motion into horizontal and vertical components. Synopsis Neil, looking the other way while riding on a skateboard, hits a fire hydrant and goes flying. Birdley explains to him that he remained in inertia while the skateboard was stopped by the fire hydrant. Main Ideas 1. Objects in motion can be in inertia. 2. As Neil hit the fire hydrant, he kept going forward at the same velocity because no horizontal forces were acting on him. 3. Although Neil s horizontal velocity remained the same, his vertical velocity changed somewhat: first due to the upward push of the skateboard, and then due to gravity. Vocabulary inertia force velocity Dr. Birdley, Neil Characters Teacher s Notes Before reading this comic, it is helpful for students to be familiar with the horizontal and vertical components of velocity. This is covered in the previous unit. Neil s flight path is similar to that seen in projectile motion. Try relating Neil to other passengers on moving vehicles that stop suddenly. 82 Questions for Discussion Before Reading: 1. Suppose I have an object on a frictionless surface that extends infinitely in all directions. What happens if I give that object one push? 2. Will it eventually stop? Or will it keep going forever? If so, why? 3. Suppose you leave a soda can on the top of a car and it takes off. What would happen to the soda can if the car were to suddenly come to a halt? After Reading: 1. What happens to Neil? 2. Why does Neil remain in inertia? 3. What do seatbelts do if your car suddenly stops? How does this relate to inertia?

60 IT S INERTIA NAME: CLASS: DATE: STUDY QUESTIONS Directions: Answer the following questions to the best of your ability. 1. As his skateboard hits the fire hydrant, why does Neil continue to fly forward? Explain. 2. Describe Neil s vertical motion in the comic. 3. What forces act on Neil s vertical motion? 4. Does the skateboard remain in inertia throughout the comic? Why or why not? 5. How does inertia contribute to Neil s accident? 84

61 1. Why does a lead weight fall faster than a feather? 2. Why would two objects fall at the same speed in a vacuum tube? 3. Two objects with different shapes fall at the same speed in open air. What can you conclude about the amount of air resistance each object encounters? Copyright 2007 by Nevin Katz 87

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