1. Falling apple. 2. Ball on string. Resource 2: from The Department of Children, Schools and Families, UK.

Transcription

1 Resource 2: from The Department of Children, Schools and Families, UK. 1. Falling apple An apple is falling through the air. 1. Write down any FORCES which are acting ON THE APPLE. 2. What can you say about the SIZE of these forces? 3. Carefully DRAW in the forces on the diagram of the falling apple above. 2. Ball on string A ball is hanging from a length of string. 1. Write down any FORCES which are acting ON THE BALL. 2. What can you say about the SIZE of these forces? 3. Carefully DRAW in the forces on the diagram of the falling ball above.

2 3. Book on table A book is left on the table. 1. Write down any FORCES which are acting ON THE BOOK. 2. What can you say about the SIZE of these forces? 3. Carefully DRAW in the forces on the diagram of the table and book above.

3 Appendix 2 (Lesson 2) Resource 3: from The Physics Classroom Force Interactive: Frictionless Situations Purpose: The purpose of this activity is to investigate the variables that affect the acceleration of an object and the manner in which those variables affect the acceleration. Background: When forces are unbalanced, objects accelerate. But what exactly affects the acceleration of the object? You will explore this question by running a collection of simulations in the absence of friction. Set the friction value to 0.00 and run the following trials. Collect sufficient velocity-time information (fifth column) for determining the acceleration in the last column. Data: Trial Applied Force (N) Mass (kg) Net Force (N) Velocity-time Information Acceleration (m/s/s) Use the collected data to answer the questions in the Analysis section. 19

4 Analysis: 1. What affect does a doubling of the net force have upon the acceleration of the object? Be quantitative. (Don't just say it decreases or increases; indicate the factor by which acceleration decreases or increases.) Identify a set of two trials that support your answer above: 2. What affect does a tripling of the net force have upon the acceleration of the object? Be quantitative. Identify a set of two trials that support your answer above: 3. What affect does a doubling of the mass have upon the acceleration of the object? Be quantitative. Identify a set of two trials that support your answer above: 4. What affect does a quadrupling of the mass have upon the acceleration of the object? Be quantitative. Identify a set of two trials that support your answer above: 5. Lab partners Vera and Bill Confuzzens attempted to use Trials 5 and 8 to show the affect that a doubling of force has upon the acceleration. Explain why these two trials cannot be used to show the affect of force upon acceleration Conclusion: Consider the original question that prompted this investigation: What variables affect the acceleration of an object and in what manner do they affect the acceleration? Make a claim in which you attempt to answer this question. Then support the claim with evidence (specific references to trials of data) and reasoning in which you explain how the data support the claim that you have made. 20

5 Resource 4: adapted from Utech Outreach Coin and Card Flip Experiment Materials 1 playing card 1 cup 1 coin Procedure 1. Set the playing card on top of the cup. 2. Set the penny on top of the playing card. 3. Flick the playing card. 4. Observe what happens! Questions 1. What force(s) acted on the playing card? Gravity, my hand. 2. What force(s) acted on the coin? Gravity, the playing card transmitted a small part of the force from my hand. 3. In this experiment, what was at rest? The cup, playing card and coin before I flicked, the cup when I flicked the playing card, and the cup, playing card and coin after they fall. 4. In this experiment, what was in motion? When I flicked the playing card, the card and coin were in motion. They stayed in motion until they hit the ground. 5. Why didn t the coin move sideways as much as the card? The friction between the coin and card was small, so only a small amount of the force of my hand was transmitted. Since it was a small amount of force, the coin only moved a little 21

6 Resource 5: adapted from Latham, T. (n.d.) Egg Drop Experiment Materials: Lightweight kitchen garbage bag liners Scissors Ruler 12 sections of lightweight string 3 plastic sandwich bags 3 raw eggs Digital Camera SD card reader (or port on computer) USB Method: 1. Have students use the following directions to build three parachutes for an ordinary chicken egg: From a lightweight plastic kitchen garbage-can liner, cut out three squares. Make one square 10cm x 10cm, a second square 20cm x 20cm, and a third square 30cm by 30cm Make a parachute out of each square by tying a piece of string to each corner of the square, then attaching the other ends of the strings to a plastic sandwich bag. Place a raw egg in each of the sandwich bags 2. Students to predict which egg has the best chance of surviving a drop from about ten feet from the floor. Students should explain the reasoning behind their predictions. 3. Have students drop each unfurled egg parachute from a height of ten feet, recording with a tripod mounted video/digital camera, and then determine whether or not their predictions were confirmed. 4. Students should record their results and describe the changing forces that acted on the parachutes as they fell and the resulting changes in the parachutes motion. How did the falls of the larger parachutes differ from the falls of the smaller ones? 5. Answer discussion questions: Discussion Questions: 1. Define the terms speed and acceleration. Explain how the two terms are related. 2. How can creating and analysing graphs be useful for understanding forces and motion in objects? 3. Construct a position-versus-time graph for the following set of data: (D1= 0 m,t1= 0 sec), (D2= 7 m,t2= 3 sec), (D3= 14 m,t3= 6 sec), (D4= 21 m,t4= 9 sec), and (D5= 28 m,t5= 12 sec). Discuss how you would use this graph to determine the speed of the object being represented. 4. Is the object represented in question 3 moving with constant speed or constant acceleration? Explain how you arrived at your conclusion. 5. Debate what assumptions might be made about the unknown forces that are acting on the 22

7 object represented by the graph in question 3. Explain the reasons for each of your assumptions. 6. If the object in question 3 continued to move, explain how you might use the graph, its gradient, and the data plotted on its x- and y-axes to determine how far the object would travel in 19.5 additional seconds. 7. From the graph constructed in question 3, calculate the object s speed at three-second intervals, then use this new information to construct a speed-versus-time graph for the object. 23

8 Resource 6: adapted from College of Education, Denton, Texas, (n.d.) Construct a Balanced Mobile Objective: The learner will build a mobile made out of balanced levers. The students will make a mobile out of balanced levers. Materials: -String -4 wooden dowel rods (one 50cm long, the others at various shorter lengths) -Various objects of different weights (paper clips, keys, construction paper figures with coins attached by glue or tape, etc.) -Spring scale calculated in newtons. -Digital Camera to take a photo of final product Method: -Construct a mobile to mirror the diagram above -You can insert any value into A and B as long as A times the effort (2 m) equals B times the resistance arm (8 m). The product of the resistance arm and resistance force must equal the product of the effort arm and effort force. If B is 2, then 2(resistance force) x 8 (resistance arm) = 16. The product of the effort arm and effort force must also be 16, so A would have to be 8. The total effort force hanging from the top arm of 4m would be: = 130. The product of 130 (total effort force) x 4 m (effort arm at the top) = 525. Therefore the resistance arm (8 m) x the resistance distance must equal 525. (8 x resistance force = 525) = 65, so C is 65 kg. -Take a photo of the final mobile to use in Lesson 3. Discussion: 1. What weights did you end up using to balance the mobile? 2. What kind of application could this be used for on a journey to or life on another plane 24