GLIDING ON AIR (1 Hour)

Transcription

1 GLIDING ON AIR (1 Hour) Addresses NGSS Level of Difficulty: 4 Grade Range: 3-5 OVERVIEW In this activity, the students will construct a simple hovercraft. They will learn how friction helps or hinders the movement of the hovercraft. Topic: Friction Real-World Science Topics: An exploration of how friction affects the motion of an object. An introduction to a type of transportation that uses air for motion. Objective Students will gain an understanding of how a simple hovercraft uses the forces of motion to move. Materials Needed for Student Activity Materials Needed for Each Team of 2 to 4 students 3 round balloons 3 16 oz. soft drink, or water bottle 3 Compact Discs (C.D.) rubber sole shoe string 8 1/2 x 11 paper Tape Pencil Teacher Materials Needed Per Class power drill, with different size drill bits (3/32, 7/32, and 1/2 ) craft knife (teacher only) hot glue gun, with glue sharp scissors safety glasses drill block 1

2 GLIDING ON AIR (1 HOUR) Teacher Preparation Before the activity an adult will need to use a sharp craft knife, hot glue gun, and a power drill to prepare each group s materials. First, cut the neck section of the bottle. Later in the activity the students will place the balloon over this piece, so it is important that there are no jagged edges. You will probably need to trim the edges with the scissors. Next, hot glue the flat side of the bottle cap to the center of the C.D. Then, turn the C.D. so that the bottle cap is laying flat on a drill block. If you drill from the opposite side the hovercraft will not work. Finally, put on your safety glasses and drill a hole through the center of each bottle cap. Since there will be three hovercrafts per group, you will need to drill three different sized holes for the bottle caps. You will need a small, medium, and large hole. (If you do not have a power drill, you can also put holes in the caps by using a hammer and different sizes of nails). 2

3 STEPS FOR GLIDING ON AIR NGSS Three-Dimensions Science and Engineering Practices Disciplinary Core Ideas Crosscutting Concepts Structure and Function PS2.A: Forces and Motion Structure and Function The shape and stability of structures of natural and designed objects are related to their function(s). Objects pull or push each other when they collide or are connected. Pushes and pulls can have different strengths and directions. Pushing or pulling on an object can change the speed or direction of its motion and can start or stop it. An object sliding on a surface or sitting on a slope experiences a pull due to friction on the object due to the surface that opposes the object s motion. The shape and stability of structures of natural and designed objects are related to their function(s). 3

4 STEPS FOR GLIDING ON AIR 1. Warm-up Activity: Open the class by showing the class a picture of a hovercraft. Students may or may not know what it is. If they do not know give them a hint, tell them that it is a type of transportation. Ask them the following questions: How does it go? Where would you drive it? Why do you think people would use this machine for transportation? Explain to the students that the object in the picture is a hovercraft. Hovercrafts are vehicles that travel on a cushion of air. They can be used on the land and water. The craft is lifted up by a cushion of air, and a powerful propeller on the back of the craft that provides enough thrust to move it forward. 2. Word Web: Place the word friction on the chalkboard or interactive whiteboard. Have the students brainstorm their understanding of friction and place their responses on the word web. 3. Distribute the Gliding on Air handout and materials to each group of 2 4 students. 4. To demonstrate friction have a student from each group remove a shoe with a rubber sole. Have them tie a string to the shoe and pull it gently on the floor. (Use a carpeted area for the best results.) After they have pulled the shoe with the string, have them trace the shoe on a piece of paper. They should cut out the traced shoe and tape the paper to the bottom of the shoe. Have the students pull the shoe gently across the floor again. Ask: Which trial involved more friction? Explain why. Which trial was less difficult? Explain why. What is the purpose of the tread of the shoe? What are some ways to reduce friction on a shoe? What are some ways to increase the friction of a shoe? 5. Have the group put the shoe to the side while they construct their hovercrafts. Explain that air can be one way to reduce friction between two surfaces. 4

5 STEPS FOR GLIDING ON AIR 6. Have the groups stretch a balloon over the neck of the bottle and blow it up from the lip of the bottle. After the balloon is fully inflated, the students should pinch the balloon so air does not escape. 7. Have the groups select the C.D. and bottle cap with the small hole. They should screw the inflated balloon into the bottle cap that is glued to the C.D. 8. Have the students place the hovercraft on a flat surface and release the balloon. As the balloon is deflating have them use a finger to gently push the C.D. across the surface. Have them observe and record their results. 9. Have groups repeat steps 6-8 again with the medium and large bottle cap holes. 10. Have the groups select their best performing hovercraft. Have the groups take turns racing their hovercrafts on a flat surface. This time they should only blow on the C.D. to propel the hovercraft forward. 11. Wrap-up Activity: Review the results with the students. Ask students to look at their recorded observations and decide which hovercraft design worked the best. Ask: Which size hole works best for the hovercraft design? Why do you think this size is the best? Explain. Gliding on Air Extension Activity Have the students work in groups to improve their hovercraft design. Have them consider new ways of controlling speed, direction, and distance. 5

6 GLIDING ON AIR BACKGROUND INFORMATION What is a hovercraft? A hovercraft is a vehicle that can travel above the surface of land or water. It accomplishes this by gliding over the surface with a cushion of air. This type of vehicle is used to move people and objects across swamps, bodies of water, beaches, and deserts. What is friction? Friction is a force between two objects that affects the movement between them. There are actually two types of friction, static and kinetic. Static friction is the friction between objects that are not moving. An example of this would be a heavy box sitting on a carpeted slope. The box does not move because of the traction between the carpet, floor, and box. Kinetic friction is the friction created by moving objects. An example of this would be rubbing your hands together to create heat. Hovercrafts are useful because they are able to reduce the friction between the vehicle and various types of terrain. 6

7 GLIDING ON AIR TEACHER HANDOUT Shoe Activity You will do the shoe experiment two different ways. Record or draw your observations. Trial #1 (Shoe) Trial #2 (Shoe with paper sole) Results will vary. Results will vary. Which trial involved more friction? Explain why. Trial #1 involves more friction because of the type of sole that is on the rubber shoe. It was designed with more traction to prevent slipping. Which trial was less difficult? Explain why. Trial #2 involves less friction because the sole design is completely covered which blocks the traction of the shoe. This smooth surface decreases the amount of friction and traction between the shoe and the floor. What is the purpose of the tread of the shoe? The purpose of shoe tread is to provide more traction. Traction keeps the shoe from slipping, but it all allows the wearer to stop quickly. What are some ways to reduce friction on a shoe? Answers will vary. The students may respond with a flat sole, or place wheels on the shoe. What are some ways to increase the friction of a shoe? Answers will vary. The students may suggest adding additional tread, or adding an adhesive to the bottom of the shoe. 7

8 GLIDING ON AIR TEACHER HANDOUT Hovercraft Trials You will test the hovercraft three different ways. Record or draw your observations. Trial #1 (Small Hole) Trial #2 (Medium Hole) Trial #2 (Large Hole) Results will vary. Results will vary. Results will vary. Which size hole works best for the hovercraft design? Results will vary. Why do you think this size is the best? Explain. Results will vary. Gliding on Air Extension Activity Improve your hovercraft design. Think of new ways to control speed, direction, and distance. Draw and explain your new design. Designs will vary. 8

9 GLIDING ON AIR STUDENT HANDOUT Name: Date: Shoe Activity You will do the shoe experiment two different ways. Record or draw your observations. Trial #1 (Shoe) Trial #2 (Shoe with paper sole) Which trial involved more friction? Explain why. Which trial was less difficult? Explain why. What is the purpose of the tread of the shoe? What are some ways to reduce friction on a shoe? What are some ways to increase the friction of a shoe? 9

10 GLIDING ON AIR STUDENT HANDOUT Hovercraft Trials You will test the hovercraft three different ways. Record or draw your observations. Trial #1 (Small Hole) Trial #2 (Medium Hole) Trial #2 (Large Hole) Which size hole works best for the hovercraft design? Why do you think this size is the best? Explain. Gliding on Air Extension Activity Improve your hovercraft design. Think of new ways to control speed, direction, and distance. Draw and explain your new design. 10