Systems and Simple Machines Student Activity Book Answer Key

Transcription

1 Answer Key Pages 3-6 Systems 1. Answers vary. Examples include: solar system, the body systems, etc. 2. Answers vary. Definitions may include the idea that the parts work together to do a job. 3. Answers vary. 4. The spoolmobile is made up of many different parts. Each part of the spoolmobile has a job to do so the spoolmobile can move. The parts of the spoolmobile interact or work together to make the spoolmobile move. Pages 7-9 Spoolmobile on the Go! 1. Chart of observations and questions will vary. A sample chart: Observations as you watch your spoolmobile on the go Goes in a straight line and then curves as it stops moving. Questions that come to mind as you make your observations Can the spoolmobile turn in a circle? The rubberband untwists as the spoolmobile moves forward. Would changing the number of times I turn the rubberband make the spoolmobile go a further distance? 2. Investigation Question: Based on the question the students chose to investigate. An example could be: Will the spoolmobile travel a further distance if I turn the rubberband more times? 3. Variable listed should be the one thing the students are changing in their investigation. Based on the question above, the variable would be increasing the number of turns of the rubberband (i.e. 10x, 20x, 30x, 40x). 4. Constants listed should be the various things the students are keeping the same in their investigation. Based on the question above the constants would include: the same spoolmobile, release the spoolmobile on the same surface, release spoolmobile in the same location. 5. Predictions will vary. A sample based on the question above would be: If I turn the rubberband more times, then the spoolmobile will move a farther distance. 6. Chart/Graph 7. Conclusions will vary. Students should answer the following questions in their conclusion: What changes were made to your system (spoolmobile)? How did those changes affect the system? (answer your investigation question) Do you see a pattern in your data? How do you explain your results? Sample Conclusion: In my investigation I changed the number of times that the rubberband was twisted on my spoolmobile to see if it would travel farther. I found that the spoolmobile traveled farther the more I twisted the rubberband. When I twisted the rubberband 10 times it moved 20 cm. When I twisted the rubberband 20 times the distance increased to 35 cm. Twisting the rubberband 30 times made the spoolmobile travel 50 cm. When I twisted the rubberband 40 times, it traveled 90 cm. The more I twisted the rubberband, the more energy was stored in the rubberband. When I let go of the spoolmobile, it was able to move farther with the greater amount of energy. Pages Machines and Work 1. Answers vary. Sample: I grabbed both sides of the dotted line on the rectangle and slowly ripped the paper along that line. The edges were jagged. 2. Answers vary. Sample: I placed the scissors in one corner of the rectangle. I pushed down on the handles. The paper was cut along the dotted line the two times I opened and closed the scissors. 1

2 Systems and Simple Machines 3. The scissors was easier. 4. Answers vary. Sample: I looked for the hole in the mesh. I took the end of the thread and tried to push it through the very small hole with my fingers. 5. Answers vary. Sample: I threaded the thread through the eye of the needle. Then I pushed the needle through the very small hole of the mesh. The needle and the thread went through the mesh. 6. The needle was easier. 7. Answers vary. Sample: I took my fingernail and tried to scrape the wood off the end of the pencil. 8. Answers vary. Sample: I put the pencil into the pencil sharpener. The sharp edge of the sharpener sliced away at the wood at the end of the pencil. 9. The pencil sharpener was easier. 10. Answers vary. Sample: I put the end of the clay ball in each of my hands. I used my muscles to pull the clay ball apart. I had to twist the clay a few times before it finally broke apart. 11. Answers vary. Sample: I held the knife in my hand and placed the sharp end of the knife on the clay. I pushed down on the knife and the knife moved downward into the clay until it was split in half. 12. The knife was easier. Pages Simple Machines 1. A machine is an object made of many parts that have a job. The parts interact to help do work. 2. Force is a push or a pull. 3. Work is what is done when a force moves a load from one place to another. 4. A load is the object to be moved or lifted. 5. Answers vary. 6. inclined plane 7. lever 8. wedge 9. wheel and axle 10. screw 11. pulley 12. Answers vary. Student descriptions of how they would use the simple machine should be accurate. Pages Lever 1. approximately 11 washers 2. approximately 3 washers 3. approximately 1 washer 4. The closer the load is to the fulcrum the less washers (force) are needed to lift the load g 5g 6. I moved the 10 gram mass closer to the fulcrum. 7. Approximately 13.4 cm 8. Approximately 6.7 cm g g Approximately 13.4 cm Approximately 6.7 cm 2

3 12. The data shows that the distance between the center of the 10 gram mass and the center of the fulcrum is half of the distance between the center of the 5 gram mass and the center of the fulcrum. 5 gram mass is half the mass of the 10 grams, as well. Same is true for the 10 gram mass and the 20 gram mass. 13. Answers vary. Sample: The heavier mass needs to be closer to the fulcrum if the lever is going to balance. If we are on the seesaw on the playground with a heavier person, the heavier person needs to be closer to the fulcrum in order for the seesaw to balance. Pages Wheel and Axle 1. Answers vary. Sample: Sports racing cars motorcycles bike racing rollerblades rollerskates School school bus scooters in gym door handles Transportation cars bikes trains steering wheel of car Home screwdriver fan wagon 2. wheel axle Pages Friction 1. Friction is a force that slows down objects when they rub against each other. 2. Student pictures should show that when the car is on its wheels it is able to move quickly, smoothly, and at a faster pace. When the car is off its wheels, the friction on the desk makes it harder to push, and the car does not go very far Answers vary. Sample responses on chart: Surface Describe how the car moves. without wheels and axles with wheels and axles Rate from 1-4 How hard is it to move the car on each surface without wheels and axles? 3. Sandpaper Difficult to move, feel a lot of resistance, feels rough 4. Felt Feels like the car is being held back, feel resistance 5. Carpet Feels like the car does not move easily, hard to move Easier to move Rolls smoothly Rolls smoothly Answers vary. Should show that it is easiest to move the car without wheels and axles on plastic bag. 6. Plastic Bag Feels smoother to roll without wheels and axles on this surface, car doesn t keep rolling Easy to move, smooth movement 3

4 Systems and Simple Machines 7. Approximately 1 cm 8. Approximately 9 cm 9. More of the car is touching the surface when the car is off its wheels. Only a small part of each wheel is touching the surface. 10. Wheels reduce the amount of friction because the wheels cause motion by rolling. As a wheel rolls, only a small amount of the wheel touches the ground. There is less space for the object and the ground to rub together. The box has a large area touching the ground, so there is more friction when moving the box without wheels along a surface. 11. Answers vary. Sample: Wheels and axles help us do work. They make our work easier by reducing friction between the ground and the load we are carrying. For example, when I moved the cardboard car without wheels, the greater amount of friction between the car and the desk made it hard to move the car. When I moved the car with wheels, it was much easier. The wheels reduce the friction by rolling. Only a small amount of the wheel is touching the ground at one time. When the car is not on its wheels, the top of the whole car is touching the surface. So there is more friction. Pages Pulley 1. wheel axle pulley string load wheel string axle pulley load Fixed pulley Movable pulley 2. It is difficult to lift the load up with just two fingers. 4

5 Systems and Simple Machines 3. the force is being pulled. the load is moving. the force is being pulled. the load is moving. Fixed pulley Movable pulley 4. It feels easier to move the load with the pulley. 5. Answers vary depending on the pulley system they are working on at this point in the activity. For example, if they are working on a fixed pulley, students may say that they are pulling down on the rope to lift the load rather than pulling up on the basket. If they are working on a movable pulley, students may say that they are pulling up on the load, and they pulled up on the basket. 6. See answer to question Answers vary depending on the pulley system they are working on at this point in the activity. Overall, students should feel that it is easier to lift the load with the pulley system. 8. Answers vary. Sample answers may include that it feels easy to lift the load with the fixed pulley because we are working with gravity (pulling down) not against gravity (pulling up). We are actually using less force when using the movable pulley because one end of the rope is attached to the hook that doesn t move. That hook is holding half the load. So the force I am using to lift the load is the amount needed to lift half the weight of the load. 9. Answers vary. Pages Spring Scale 1. 6 N 2. 1 N 3. 9 N 4. 5 N 5. 3 N 6. See Spring Scale 5

6 7. I change the amount of gram masses that are being lifted. 8. The constants in this investigation include the same spring scale and basket and lifting the basket the same distance from the desk. 9. Predictions vary. Sample: If I add more mass to the basket, then it will require more force to lift that mass. 10. Chart/graph results will vary. Data results should show that as the amount of gram masses increase, the amount of force needed to lift the gram masses also increases. 11. In this investigation, we found that as we changed the mass of the load being lifted the amount of force needed to lift the load also changed. When the amount of the mass increased, the amount of force needed to lift that load also increased. (Students should include specific evidence from their data.) Pages Inclined Plane 1. An inclined plane is a flat surface raised on one end to connect one level to a higher level. It is used to move a load to a higher level with less force. 2. The variable in the investigation is the different heights of the inclined plane. 3. The constants are the same load, the same pull of the load, the same spring scale to measure force, etc. 4. Answers on the data chart will vary depending on the heights students choose for their inclined plane. Results should show that the steeper the inclined plane, the more force was needed to move the load to the top of the inclined plane. Students should also see that when using the inclined plane, less force is needed to move the load to the top of the ramp. However, the load has to travel a longer distance on the inclined plane to reach the desired height. For example, if the height of the ramp is 14 cm. It takes more force to lift the load straight up to 14 cm. When using the inclined plane, the length of the ramp is 44.5 cm. The distance to move the load is greater, but the force required is less. 5. Graph of results should correlate to data table. 6. Answers vary. Sample: An inclined plane can help do work by moving a load to a higher level with less force. From the data, I see that when we lifted the load straight up it took a greater amount of force than if we used an inclined plane to lift and move the load. Less force is used to lift the load with an inclined plane, but the load has to move a greater distance. So less force is needed over a longer distance. The steepness of the inclined plane determines how much force is needed to move/raise the load. The steeper we made the inclined plane, the more force was required to move the load up the incline. Pages Wedge 1. Student drawings should show the triangle block cutting through the clay easier than the rectangle block. The rectangle block smashes the clay flat. 2. It was easier to cut the clay with the triangle block. The thin edge of the triangle block moved through the clay. 3. Student drawings should show the plastic knife cutting through the clay easier than the rectangle block. The rectangle block smashes the clay flat. 4. It was easier to cut the clay with the plastic knife. The thin edge of the plastic knife moved through the clay. 5. Scissors: The blades of the scissors are wedges. They cut through paper. 6. Shovel: The edge of the shovel is a wedge. It splits through soil. 7. Arrow: The point of the arrow is a wedge. It splits through a dart board and makes a hole. 8. Pushpin: The point of the pushpin is a wedge. It splits through a corkboard and makes a hole. 9. Answers vary. Pages Screw 1. Student drawings should show the threads of the screw vs. the smooth metal of the nail. 2. Both the screw and the nail are made of metal. Both are simple machines. Both are similar lengths. Both are used in building or construction. 3. The screw has threads on it while the nail does not. The screw has a groove on the top of it for a screwdriver and the nail does not Drawings will vary depending on the items at each station. 6

7 Pages Compound Machine Improve the Design Test the Prototype Identify the Problem Engineering Design Process Identify Criteria and Constraints Brainstorm Possible Solutions Build a Model or Prototype Develop the Design Step 1: Students restate the problem at the top of page 44. Step 2: Answers vary but may include Sparky must fit into device, must be able to hold Sparky s weight, easy to use, etc. Step 3: Answers vary but may include safe use for Sparky, machine should be able to be attached to or used near the treehouse, can be used over and over again, etc. Step 4: Students draw pictures of group ideas. Important details/measurements should be noted. Step 5: Answers vary. Students reflect on their experience with the design process. Pages Summary Page 1. Levers help me to raise and move a load. Student draws a picture of a lever. 2. Wheel and axles help me to move a load with less friction. Student draws a picture of a wheel and axle. 3. Pulleys help me to raise or lower a load. Student draws a picture of a pulley. 4. Inclined planes help me lift and move loads with less force. Student draws a picture of an inclined plane. 5. Wedges help me to split apart or cut a load. Student draws a picture of a wedge. 6. Screws help me to keep things held together. Student draws a picture of a screw. 7. A compound machine is a machine made up of two or more simple machines. 8. Answers vary but may include a car, a bike, a wagon, scissors, etc. Copyright 2011 by the Board of Cooperative Educational Services for the Second Supervisory District of Monroe and Orleans Counties, Elementary Science Program. All rights reserved. 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, recording, or otherwise, without the prior written permission of Monroe 2 Orleans BOCES, Elementary Science Program. 7