The purpose of this lab is to investigate the impact of changing velocity on the centripetal force of a swinging pendulum.
Theory
A pendulum swings in a circular path. This means that the pendulum bob is acted on my a centripetal force. It is the tension in the metal rod that causes the circular path to occur. The net force at the bottom of the pendulum's swing is a combination of the tension of the rod and the force due to gravity of the object. As the pendulum swings, the velocity of the bob changes, which then changes the centripetal force.
Centripetal force is the force of an object as it moves in a circular path.
Percent difference is the percentage of difference between two values.
Free Body Diagram of the experiment
Experimental Technique
In order to investigate the effects of changing velocity on the centripetal force of a swinging pendulum bob, we first had to measure several quantities. A rotary motion sensor, a force sensor, a photogate, a mass set, a threaded road, and claps and rods were utilized in this experiment. However, the rotary motion sensor was not used for its sensor but itsead for its swinging capabilities.
To find velocity, we first gently swung the pendulum to start its movement then measured its velocity using the photo gate and its force using the force sensor. These measurements gave the velocity at each point as well as the actual centripetal force.
Data and Analysis
Below is are the graphs for centripetal force and velocity.
(Above) All values found - Mass, velocity, radius, and actual centripetal force were all found without any calculation. (Below) Centripetal Force Sample Calculation
(Below) Percent Difference Sample Calculation
Conclusion
Overall, this lab was pretty successful. It was found through investigation that changes in velocity do indeed affect centripetal force. As velocity decreases, so does the centripetal force of the swinging object. However, despite attempts to make the experimentation as precise as possible, the percent difference found was still relatively large. This could be due to a wobble in the rod as the pendulum swung. In the future, this could be avoided by finding a better way to secure the rod and other parts.
References
Giancoli, D. (1998). Physics: Principles with applications (5th ed.). Upper Saddle River, N.J.: Prentice Hall.