Helicopter & Launcher

Transcription

1 Helicopter & Launcher Category: Physics: Force & Motion Type: Make & Take Rough Parts List: 2 Large craft sticks or paint paddles 12 Dowel, ¼ 1 Dowel, 1 long, ¼ 1 Wood block, 8 x 1 x 1 1 Wood block, tiny 1 Cardstock or playing card Small finishing nails (no head, or chop off the head later) String Drill with 15/64 bit Glue Video: How To: Drill a hole in the center of the craft stick, slightly smaller than the dowel. Insert a dowel into the hole.

2 Cut two 3.5 x 1.25 pieces out of cardstock or playing cards. Make a mark 1 away from 1 end of each piece. Attach the card stock to the bottom side of each end of the craft, on opposite sides. The end of the craft stick should align with the 1 mark. Curve the card stock so that it resembles a fan or helicopter blade and will push air down as it spins. Helicopter is now ready to fly with a hand launch. Drill a hole into the tiny block. This hole should be big enough for the dowel to enter loosely. Attach the tiny block to the launcher. Attach a handle to the launcher.

3 Hammer two nails into the other end of the launcher. Drill a hole through the launcher about 1 below the nails. Attach a 1 dowel just below the nails. Wrap a small piece of tape around the end of a string and thread it through the hole in the launcher. Insert the bottom of the helicopter into the hole in the small block and let it rest on the launcher. Wind the string around the helicopter in the opposite direction of how it will fly. Here is shown a bit of tape at the tip of the string which makes threading it through the hole and wrapping it easier.

4 A wound- up helicopter will look like this. Pull the string to release the helicopter and watch it fly. Fine Points: Helicopter works fine launching by spinning the dowel between the palms of your hands. The launcher is optional. Adjust the bend and shape of the blades to maximize the flight. Concepts Involved: Air is real. You can t see it, but it moves things. As the helicopter begins to move, the air that it encounters makes it spin around and fall slower. If the blades are bent correctly, the air pushes them to make the helicopter go around. Focus Questions: 1. What do you think would happen if you made the helicopter heavier at the bottom? 2. How could you make the helicopter go up farther? 3. What are some differences between this helicopter and a real helicopter? 4. What could you change to make the helicopter spin faster? Elaboration: As this toy helicopter falls, the blades encounter air. The blades are at an angle, so that each little bit of air that hits them bounces off and pushes them to the side. If you have them bent correctly, each one will be pushed in the opposite direction, causing the helicopter to spin. The air also pushes up the blades, causing the helicopter to fall slower than if it were just tumbling randomly. Real helicopters do this in emergencies. If a helicopter s engine fails, the recovery procedure is to begin autorotation. This simply means that instead of the engine turning the blades, the air flowing past the

5 falling craft will turn the blades. In most cases, this provides enough upward force to insure a slow decent, allowing the pilot to find a suitable space below for an emergency landing. This toy requires air to function. If you tried it on the moon, here is what would happen: It would rise to six times the height it rises to on earth, because the moon s gravity is six times less than the earth s. Then it would fall back to the earth without any spinning at all, because there is no air on the moon. Let s follow the energy used in this project. You provide the original energy to launch this helicopter.your body got this energy by metabolizing the food you ate earlier. When you spin the string in the launcher, it holds potential energy. When released, it gives this energy to the helicopter. The helicopter begins accelerating upward. As the helicopter leaves either your hand or the launcher, it is traveling as fast as it will go during its flight. The potential energy of the launcher has been converted into kinetic energy (KE = 1/2 mv 2 ). The helicopter slows down as it continues upward because gravity is pulling steadily downward on it. It loses kinetic energy as it gains potential energy of height (PE = mgh). At its highest point, it stops moving up and has lost all kinetic energy. It holds the maximum potential energy of height it will have. It then returns down, exchanging that potential energy back for kinetic energy as it accelerates toward the ground. If the blades spring out properly, they encounter air. Some of the helicopter s potential energy goes into pushing the blades around through the air, so the speed (and kinetic energy) of the helicopter is less on the way down. Since it is rotating though, it also has rotational kinetic energy. Upon impact with the ground, all remaining energy is converted to heat. You won t feel this heat because there is not much energy involved. But if you clap your hands together hard, you ll feel the heat of impact. Links to k- 12 California Content Standards: Grades k- 8 Standard Set Investigation and Experimentation Scientific progress is made by asking meaningful questions and conducting careful investigations. As a basis for understanding this concept and addressing the content in the other strands, students should develop their own questions and perform investigations. Grades k- 12 Mathematical Reasoning: 1.0 Students make decisions about how to approach problems: 1.1 Analyze problems by identifying relationships, distinguishing relevant from irrelevant information, sequencing and prioritizing information, and observing patterns. 1.2 Determine when and how to break a problem into simpler parts. 2.0 Students use strategies, skills, and concepts in finding solutions: 2.1 Use estimation to verify the reasonableness of calculated results. 2.2 Apply strategies and results from simpler problems to more complex problems. 2.3 Use a variety of methods, such as words, numbers, symbols, charts, graphs, tables, diagrams, and

6 models, to explain mathematical reasoning. 2.5 Indicate the relative advantages of exact and approximate solutions to problems and give answers to a specified degree of accuracy. 3.0 Students move beyond a particular problem by generalizing to other situations: 3.1 Evaluate the reasonableness of the solution in the context of the original situation. 3.2 Note the method of deriving the solution and demonstrate a conceptual understanding of the derivation by solving similar problems. 3.3 Develop generalizations of the results obtained and apply them in other circumstances. Grade 2 Standard Set 1. Physical Sciences: The motion of objects can be observed and measured. 1.c Students know the way to change how something is moving is by giving it a push or a pull. The size of the change is related to the strength, or the amount of force, of the push or pull. 1.d Students know tools and machines are used to apply pushes and pulls (forces) to make things move. Grade 3 Standard Set 1. Physical Sciences (Energy & Matter) 1.d Students know energy can be carried from one place to another by waves, such as water waves and sound waves, by electric current, and by moving objects. Grade 8 Standard Set 2. Forces: Unbalanced forces cause changes in velocity. 2.a Students know a force has both direction and magnitude. 2.c Students know when the forces on an object are balanced, the motion of the object does not change. Grade 9-12 Physics Standard Set 1. Motion & Forces Newton s laws predict the motion of most objects. 1.b Students know that when forces are balanced, no acceleration occurs; thus an object continues to move at a constant speed or stays at rest (Newton s First Law).