Whirly Durly Lab
Partners: Emmy Xu and Jasmine Zhao
Lab Performed: December 3, 2021
Lab Written: December 5, 2021
Variables and Questions
The hypothesis or question we are trying to answer was "How does tangential speed affect the turning acceleration of a bob?" In this experiment, the independent variable, or the variable we intentionally change, is the tangential speed of the rotating string. Tangential speed is velocity or the speed at which an object is moving tangent to the path. The dependent variable or the variable that is changed as a result is acceleration or the change of velocity of an object as time passes. The control variables, or the variables that remain the same, are the mass of the bob, the radius, and the same planet.
Developed Method and Procedure
In order to calculate the tangential speed, we had to measure the number of rotations that occurred in a certain about of time, while also keeping the bob at a consistent speed. In order to do that, we used a metronome, like used in music, to keep the bob at a consistent speed that could be adjusted based on bpms (beats per minute). Then, one person would count and see long it took for 20 rotations, in order to ensure the most precise time to rotation ratio. As for the procedure, we adjusted the bpm of the metronome, and waited until the person had been circling the bob at the rate of the metronome, we started the Logger Pro force graph to find out the acceleration, and finally started the timer for the 20 rotations. We repeated this for 5 different bpms, and recorded the data accordingly. From the Logger pro graph, we estimated the average y coordinate that corresponded to the acceleration.
Raw Data and Lab Diagram
Processed Data and Graph
In order to calculate the tangential speed, we decided the numbers of rotations by second, multiplied by 2pi (to convert into radians), and multiplied it by the radius.
Drawing Conclusions and Final Conclusions
From the graph, we can infer than the relationship between tangential speed and acceleration is exponentially increasing, becoming steeper and steeper. This means as tangential velocity increases, acceleration increases extremely fast as velocity continues to increase. With this known relationship, we can apply this outside of the classroom to real life examples of things orbiting into a circle. For example, many planets that orbit the sun or other moons that orbit the planet. If a planet increases in speed, the acceleration will continue to increase exponentially. We can take this relationship into account when solving problems involving tangential speed and acceleration. To check our work, we can calculate the tangiental speed and see if the accelertaion corresponds according using the given equation on the graph (a=2.0368*v^2).
Evaluating Procedures and Improving the Investigation
The procedure was pretty flawed, as it took a second for the person to get in the correct speed, as well as keeping the radius constant at the same time. In addition, we had to redo several of the trials because the person wasn't able to keep up the speed and or the velocity. In addition, the timer had to count the number of revolutions and stop at the same time, which could've altered the angular speed. In order to improve the investigation, I would create a new bob with a set radius that is unable to change, using a hard piece of plastic glue to the string at a specific length. In addition, I would create a wider range of BPMs, and repeat each trial at least three times to ensure accuracy. In addition, I would get another person, one to be the counter, and the other to be the timer, in order to ensure accuracy once again.
From the graph, we can infer than the relationship between tangential speed and acceleration is exponentially increasing, becoming steeper and steeper. This means as tangential velocity increases, acceleration increases extremely fast as velocity continues to increase. With this known relationship, we can apply this outside of the classroom to real life examples of things orbiting into a circle. For example, many planets that orbit the sun or other moons that orbit the planet. If a planet increases in speed, the acceleration will continue to increase exponentially. We can take this relationship into account when solving problems involving tangential speed and acceleration. To check our work, we can calculate the tangiental speed and see if the accelertaion corresponds according using the given equation on the graph (a=2.0368*v^2).