Balloon Rocket Motion Experiment

Transcription

1 1 Balloon Rocket Motion Experiment Abstract: The motion of a Balloon Rocket can be drastically altered when different amounts of weight are added. In this experiment, I added various weights to test the differences in velocity, and how weight affect the velocity during a certain time frame of the video. The manipulated variable during this experiment is the weight of the balloon rocket, while everything else remained controlled. I used four different weights (6.35 g, 9.74 g, g, g) to test the difference in velocity. After marking and analyzing the data I collected, I have learnt that weight truly affects the velocity of a balloon rocket and that the more weight a balloon rocket is carrying, the less velocity it has. Question: How does weight affect the velocity of a balloon rocket as it travels across a wire in a certain time frame? Objectives: To create a controlled experiment with one independent or manipulated variable related to motion. To use a controlled experiment on motion to learn how to make expectations of graphs of motion, and to mark videos to create observations of graphs of motion. Materials: 1 balloon Straws Scotch Tape Balloon Pump Fishing Wire Camera 4 metal rods/weights (6.35 g, 9.74 g, g, g) Variables: Controlled Variables: Size of balloon Balloon rocket The amount of air pumped into the balloon rocket Time Frame Independent/Manipulated Variable: Weight of Balloon

2 2 Figure 1 Sketch of experiment. This should clarify the method/procedure Procedure/Method: 1. Set up the fishing wire along a surface. It is preferable to use to walls and tape a wire across. Be sure that it can hold the weight of a balloon rocket. Try to minimize the movement of the wire as much as possible. 2. Cut the straw across (length wise) so you can hook it on to the fishing wire. 3. Tape the straw onto the wire while making sure it can move across the wire and the tape isn t stuck to the wire. 4. Pump the balloon 10 times using a balloon pump. 5. Tape balloon to straw while making sure no air escapes. 6. Let the rocket go along the wire. Be sure to film its motion! 7. Repeat the process 4 times using different weights (6.35 g, 9.74 g, g, g). Do not change the position of the camera. Be sure that the camera films the exact same distance. To ensure that, place some tape in front of the camera so that u won t lose its position. NOTE: weights do not have to be the same as specified in the lab. Tips on how to control the experiment: Always tape the straw onto the center of the balloon to prevent the balloon being unbalanced. This is not good because it will increase the friction of the balloon. Try to tape the weight on the center of the balloon to prevent an increase in friction. Use a more rod shaped weight rather than a weight like the one in figure 1 so that the weight will be more spread out. This should decrease the chance of unnecessary friction. Make sure not to change where the camera is. This way the camera will always record the same distance in which the balloon rocket is traveling.

3 3 Expectations: Figure 2 Predictions for Position X. The origin is on the left side where the rocket starts. My Expectations for the position of the Balloon Rocket with different weights it very simple. First, I have decided to set the origin of my experiment on the left, where the balloon rocket begins. I predict that with more and more weight on the balloon, the balloon rocket will go a less great distance and stop sooner (figure 2). This is because with the added weight, the friction of the straw on the wire will increase, making the balloon rocket travel a smaller distance and stop sooner. I also feel that the position will increase very quickly because there will be a great release of air right when I release the balloon. NOTE: none of the numerical values in the graph above are true (except for the added value of weight).

4 4 Figure 3 Predictions for Velocity X. The origin is on the left side where the rocked starts Figure 3 shows my expectations for the velocity of the Balloon Rocket as it travels across a wire. Again, I have set the origin as the place where the rocket begins. I have predicted that when I let go of the balloon without the weight, there will be a great increase of velocity, and then the balloon s velocity will be constant for a while as the pressure stabilizes in the balloon. Lastly, as the balloon runs out of air, the velocity will decrease as the friction of the wire will become to great to stop. This is what I think because when I let go of the balloon, the balloon will release a great amount of air, then the rate air escapes will stabilize then become less and less, which is why the velocity decreases. The balloon rocket with the various weights should perform exactly the same, except the rate of the velocity will increase less and less with more weight. NOTE: none of the numerical values in the graph above are true (except for the added value of weight).

5 5 Figure 4 Prediction of Acceleration X. The origin is on the left where the balloon starts My expectations of the acceleration are that the course of motion will be fairly similar to the velocity. This is because the motion is only horizontal. If it were like the diving man, the acceleration would be different to the velocity because each time the man changed direction, he would be accelerating. I believe that with each weight, the heavier it is, the less acceleration the balloon will have because it s inertia is increasing while its thrust or the air in the balloon remains the same. NOTE: none of the numerical values in the graph above are true (except for the added value of weight). Figure 5 Free body diagram of balloon rocket without weight. NOTE: there is actually also support force but because of the bopping up and down the balloon rocket does, support force is not always present.

6 6 Figure 6 Free body diagram of balloon rocket with weight. NOTE: there is actually also support force but because of the bopping up and down the balloon rocket does, support force is not always present. For my expectations of this experiment, I made two free body diagrams. I made one diagram based on the forces acting on the rocket without the weight (figure 5) and one diagram based on the forces acting on the rocket with the weight (figure 6). Logically I think that the only difference between the forces on the rocket without the weight and the rocket with the weight is that the amount of gravity pushing on the rocket increases with the weight. This in turn increases the amount of friction the straw of the rocket acts on the rocket, which should cause the rocket with the weight move slower that then rocket without the weight. Results: Calculations: The formula for calculating the amount of gravity on something: X kg*10= Y Newton of gravity on object Weight of initial balloon rocket: 3.48g Amount of gravity on initial balloon rocket:.0348 N Weight of balloon rocket with 6.35g: 9.83g Amount of gravity on balloon rocket with 6.35g:.0983 N Weight of balloon rocket with 9.74g: Amount of gravity on balloon rocket with 6.35g:.1322 N Weight of balloon rocket with 13.48g: 16.96g Amount of gravity on balloon rocket with 13.38:.1696 N Weight of balloon rocket with 17.48g: Amount of gravity on balloon rocket with 17.48g:.2096 N

7 7 These are examples of how I marked the videos of the trials I performed. Figure 7 Marking control video Figure 8 marking the video with 9.74g added

8 8 Figure 9 Marking Video with added2 I took the data from the marked videos and created these tables in Excel. These tables show the position of the balloon rocket with different weights and the velocity of the balloon rocket with different weights. Time No weight added 6.45g added 9.74g added 13.48g added 17.48g added Table 1 Position of Balloon between 2.45sec and 3.51 sec. Time No weight added 6.45g added 9.74g added 13.48g added 17.48g added

9 Table 2 Velocity of Balloon between 2.45 sec and 3.52 sec. Velocity Formula: (position B-position A)/(time B time A) = Velocity Mathematically speaking: V x = (X 2 X 1 ) (T 2 T 1 ) Figure 10 Graph of the position of the balloon rocket between 2.45 sec and 3.51 sec

10 10 Figure 11 Graph of the Velocity of the balloon rocket between 2.45 sec and 3.51 sec In figure 10 instead of calculating the velocity, I used the given velocity from Logger Pro. Figure 12 Graph of the average velocity in relation to various weights

11 11 Qualitative analysis During the course of this experiment, there were many factor that could/did affect the quality of my experiment. For example in the velocity graph (figure 10), the trend line of the velocity of the initial balloon rocket was drastically different from the other lines, which seem to be rather consistent. I believe this is due to the wobbling of the balloon rocket. Because of this, the balloon rocket essentially changes directions many times, which could have caused this sudden unexpected dip in velocity. Secondly, an aspect of the experiment that I didn t take into account, which could have affected the quality of the experiment, was the camera. During the actual experiment, I did not fully understand the severity of a minor jolt of the video, but while marking the video I learned that this is a very crucial variable that must be controlled! I believe that it is due to a slight, tiny movement of the camera that the balloon rocket with 9.74g added had a greater velocity than that with 6.45 g added. This can also be seen in figure 11, where the average velocity of the balloon rocket with 9.74g is higher than the average velocity of the balloon rocket with 6.45 g. Next, from my velocity graph I can predict that the acceleration of the balloon rockets as they traveled between 2.4 seconds and 3.5 seconds, that the acceleration was pretty constant (barring the balloon rocket with no weight added). I can infer this because acceleration is change in velocity over change in time. Conclusion: Through this experiment I feel that I have thoroughly understood my initial question for this experiment. I have learnt that weight truly does affect the velocity of a balloon rocket as it travels across a wire. I believe that this is because with more gravity (this means more weight!) pushing on the rocket balloon, the more friction occurs between the straw and the wire. By taking this into account and understanding that all the other forces were controlled I can conclude that the heavier the balloon rocket was, the smaller its velocity was. In my experiment, the 9.74 g added to the balloon test seemed to have a greater velocity than the 6.45 g added to the balloon test. I think that this may be due to a small jolt of the camera, which caused the video to jolt a little. From the results I have gathered, I feel that my results are quite consistent with my expectations. This might no seem so because the graphs are rather inconsistent. This is because my expectations showed the entire motion of the balloon rocket from the moment I would release it to the moment it would stop, while my graphed results only showed part of its motion, which about the middle of the balloon rocket s course of motion. If I were to do this experiment again, I feel like there are plenty of adjustments I could make. For starters, I would be more specific in my expectations and how I would work on my experiment. For example, I would take into account that because my expectations included the beginning of the motion of the balloon rocket that I should film that to for my results! Next time, I would also try to find more suitable standardized weights so that other students can perform my lab. Although, I do believe that with 4 other weights, the results would also be similar, just not the exact number as the results I got. In the future, I would also like to find an air pump

12 12 that can specifically tell me how much air has been pumped into the balloon. This way, I will be able to control my variable better. Overall, I feel that my experiment was quite successful, and it helped me to further my understanding about physics concepts.