Helicopter Investigation Essays

Helicopter Investigation Essays Helicopter Investigation Essay Helicopter Investigation Essay Aim: To investigate the factors that effect the time for a card helicopter to reach terminal velocity. Theory/Key Factors: When a helicopter wants to take off it starts its blades moving, and the blades push air under themselves until it they have enough air under them to take off. This is related to a sycamore seed, which is what I am basing my helicopters shape on. Terminal velocity is when air resistance is equal to the force of gravity acting on the helicopter. Therefore, the acceleration is zero and the helicopter falls at a constant speed. When my helicopter starts to spin it means that it has reached terminal velocity. The bigger the air resistance is on the helicopter is, the larger the surface area is, and consequently it will take longer to fall. The speed at which the helicopter falls at also depends on the conditions that I drop it in. To get round the problem of it being an unfair test if we dropped it outside, because of the wind speed, I have decided to drop the helicopter inside. The shape and size of the wings could affect the speed because some of the wing shapes might be more aerodynamic, in which case it would fall at a faster rate. In addition to this, the length of the handle of the helicopter might influence the rate at which it falls. Prediction I predict that the number of paperclips attached to the helicopter should not affect how great the terminal velocity is, or how long it takes to reach terminal velocity. This is because, as Galileos theory shows, objects of the same shape fall at the same rate in air, on earth (9.81 msec-2), regardless of mass, because there is no difference in the amount of air resistance. Hence, the helicopter should reach terminal velocity at the same time, regardless of its mass, as there is virtually no change in its shape. If it reaches terminal velocity at the same instance each time the experiment is conducted, then the terminal velocity will always be the same. This is because, if it is to follow the law V= u+at, the greater the product of at (acceleration and time) the greater the velocity (in this case terminal velocity). Since u is always 0 in our experiment, this does not influence the relationship between the time taken to reach terminal and terminal velocity, and the above reasoning st ill holds. However I predict that our experiment will support the law V= u + at, but will not support Galileos theory due to human error in measuring the accurate time of when the helicopter starts to spin and when it hits the floor. Diagram Method 1. By using my T-Shaped helicopter that I picked from my preliminary experiment, I will add one paperclip to it and then drop it from a height of five metres. * I will record the time from when I drop it until it hits the floor, in addition to this I will note down the time when it starts spinning (terminal velocity). 2. I will repeat the test three times with one paperclip, then I will put two paperclips on and do the test three times, and finally I will place three paperclips on and repeat the test three times. I do this because it means that I get more accurate results. Safe/Fair Testing To make it a fair test I will: * Use the same helicopter each time so that the wingspan and weight are the same throughout. * Drop the helicopter from the same height (five metres). * Drop the helicopter from the inside so that there is no interference from the wind. * Try to make sure that the paperclips are about the same size and that they are roughly the same weight. To make it a safe experiment I will take the following precautions: * I will look before I drop the helicopter, so that it doesnt hit anybody. * I will be careful when using the scissors to cut out my helicopter. * I will follow the laboratory rules to avoid any accidents. Preliminary Experiment By doing this experiment I hope to find which helicopter I could use in my main investigation, by investigating wingspan. Secondly, I hope to find a suitable range of paperclips with in which to conduct my experiment. I will use the same T-shaped helicopter in this experiment, as I will in the actual test, to make my experiment fair. I will drop my helicopter from a height of five metres (same in actual experiment) and repeat it three times so that I get more accurate results. Results: Wing surface area (cm2) Average time to reach terminal velocity (S) 1 paperclip 4 paperclips 7 paperclips 10 0.83 1.09 1.42 20 0.64 0.74 1.29 30 0.49 0.67 1.21 40 0.57 0.72 1.18 50 0.56 0.79 1.26 Preliminary Conclusion From my preliminary experiment I can see that overall the best helicopter wingspan for my experiment is thirty cm2 and the best range of paperclips to have on the helicopter is between one paperclip and four paperclips. I chose these two factors because when using one or four paperclips the helicopter reached terminal velocity the quickest, the and when I used a wingspan of thirty cm2 it reached terminal velocity fastest. Results Number of paperclips Time when dropped (s) Time when helicopter reached terminal velocity (s) Average time when started to spin (s) Time when it hit the floor (s) Average time when it hit the floor (s) Terminal velocity (m/sec, 1 D.P) Average terminal velocity (m/sec, 1 D.P) 1 0 0.53 0.48 2.57 2.49 5.2 4.73 0 0.48 2.48 4.7 0 0.44 2.41 4.3 2 0 0.54 0.56 2.51 2.57 3.3 5.57 0 0.56 2.59 5.5 0 0.59 2.60 5.9 3 0 0.64 0.61 2.81 2.92 6.3 6.0 0 0.55 3.01 5.4 0 0.63 2.94 6.2 * The equation that I used when calculating the terminal velocity of the helicopter (the velocity when it began to spin) was V= u+at. In this experiment: * V was the final velocity, * u was the initial velocity, 0 * a was the acceleration, which was 9.81 msec-2 (2.d.p.), the acceleration of all things under the gravitational pull of earth in air at room temperature. * t was the time taken for the helicopter to begin spinning once it was dropped. Analysis The results of our experiment show that the helicopter reached terminal velocity (on average) earliest when it had 1 paperclip attached to it (0.48 seconds), and it reached terminal velocity latest (on average) when it had 3 paperclips attached to it (0.61 seconds). This is shown in the bar graph between the number of paperclips and the average time taken to reach terminal velocity. The scatter graph between the terminal velocity and the time taken to reach it shows that the greater the time taken to reach terminal velocity, the greater the terminal velocity. This follows the law V= u+at, as the greater the product of at (acceleration and time) the greater the velocity (in this case the terminal velocity). Since u is always 0 in our experiment, this does not influence the relationship between the time taken to reach terminal and terminal velocity. The scatter graph also shows that the larger the weight of the helicopter, the later it reaches terminal velocity and hence the greater the terminal velocity. However, this does not comply with Galileos theory, which follows what I predicted. This is possibly due to human error, although this is not definite, which means that it cannot be ascertained whether this totally supports my prediction. Evaluation The evidence found cant be trusted fully for its scientific merit as there is a large possibility that a substantial amount of human error was involved. The method itself has a lot of faults due to human error. These include, the delay when starting the stopwatch for when the helicopter starts to fall, when it starts spinning and when for when it finally reaches the floor. In addition to this, the height and angle from which the helicopter was dropped from was not constant throughout the investigation, due to the fact that when I was dropping it I had my arm at different angles and at slightly different heights. As you can see from my graph, the experiment I did with two paperclips was the most accurate because the error bars are very close together. The experiment I did with three paperclips was the least precise because the error bars are spread out more. Due to Galileos theory I cant single out the anomalies because Galileo says that there should be only one correct answer, however I cant tell which one it is. To stop this from happening again, I could make my results more accurate by using a stopwatch that went to more decimal places. I could also test a wider range of paperclips so that I would be testing from no paperclips at all, until I reached an amount of paperclips where the helicopter didnt have time to start spinning.