Lab 9: Centripetal Force with a Motor

1.     Lab 9: Centripetal force with a motor

a.      Lab conducted by Mohammed Karim (author), Lynel, Richard, and Andrew.

2.     Objective –  Understand the relationship between theta (degree shown in Figure 9.1/9.2) and create a working linear equation that can be used to find the value.

3.     Theory/Introduction – We understand that the manipulation of force can cause an object to swing with a certain angle with respect to the ground. When an object connected to a string is dormant, it is perpendicular to the ground. However, as it spins faster and faster, the object begins to tilt toward the horizontal. Using the apparatus shown below, we are tasked with finding a fit.

4.     Apparatus/Procedure –

Apparatus.jpg

 

The apparatus shown above was the only apparatus used throughout the experiment. Basically, a mass hung from the string. The pole, that the string was connected to, began to spin with increasing velocities. The increasing velocities created a greater centripetal force, thereby increasing the tension and the angle it makes with the floor. We collected different values and used some trigonometry to find the angle the object made. We measured the distance the object was from the apparatus, and the height it was at. We then found the adjacent component and found the angle the string made with arccos. (Keep in mind that the length of the string was constant.) An example can be seen in figure 9.2.

After finding the values for multiple test runs, we plugged in the values on excel and loggerpro. (see figures 9.3 and 9.4) We then compared this to the conceptual data we had calculated and graphed it. (see figure 9.5)

5.     Data Tables

Figure 9.2

Figure 9.3

Figure 9.4

Figure 9.5.

6.     Conclusion – Overall, the conceptual data and experimental data were very close. The graph had a slow of 0.9371, showing that they were in line. Had the slope been a perfect one, the two results would have been the same. Of course, a much closer answer could have been reached, but like always, there were many factors that could have played a role in giving us a less than accurate result. One being the voltage that the object spins at as opposed to the velocity the object is at. This would be hard to fix as that would be more complex physics information. Another uncertainty would be wind resistance as the object is spinning fast and the friction from the wind could affect the objects ability to reach top speed, thus lowering its overall height. There is also propagated uncertainty in our measurements with height and where exactly the object should touch the ruler. These small percentages, while they may seem small can add and give us a much more precise answer. Even if there was a five percent uncertainty, that could put us at a 0.99 correlation, which would essentially show that the experimental data and conceptual data are the same.