31-03-2017: Lab 8 Centripetal acceleration with a motor

Introduction: In this lab we will be looking viewing a demonstration of an experiment using a wireless force sensor mounted onto the large rotating disk with one axis pointing toward the center of the disk. During the trials we will view the whole system rotating as the instructor makes certain modifications to the setup.

Purpose: The reason for this demonstration to determine the relationship between centripetal force and angular speed of the rotating disk. To put more simply, we need see how the rate of acceleration relates to the frequency of the disk’s rotation. In order to accurately determine the relationship, we are going to conduct 11 trials with varying measurements made to the setup. The first varying measurement marking a starting point on the disk. We do this to keep track of the number of time the disk’s rotations passes through the photogate, enable us to determine the period (time it takes to complete x number of rotations) of the disk. Second is the force sensor reading, this measurement is taken to determine the amount force it exerts when rotating on the system. To measure accurately, we attached a mass to a string and place it on the center of the disk, with the force sensor faced flat onto the disk. As the disk is spinning the sensor will record the force of the mass attached to the string while it is rotating. The final measurement we take is the distance of the mass from the center of the rotating disk, for this measurement, we look at the disk’s radius, using the string for the mass-force measurement, we record the length of the string from the center to the edge of the disk, and for each trial we increase the radius as we go on.

 Setup:

1.       Place the wireless force sensor on the disk. Zero  the force sensor with the disk rotating,.

2.       Adjust the voltage the on the power supply, turn on the scooter motor, and let the disk come up to a constant speed record the force sensor reading.

3.       Collect the period and the force data for:

. a variety of rotational masses at a fixed speed (look at the effect of changing m)

. the same mass at a fixed speed but different radii (look at the changing r)

. the same mass at a constant radius but a variety of rotational speeds (by varying the voltage from the power supply feeding the motor)—(look at the effect of changing omega).

Data Shift 

Force vs. Mass: 

The data shown here, was the reading we got from the sensor attached to the rotating disk. As you can see, the amount of force increases as we increase the the rotating speed of disk. With

the amount of force increasing , it also increased its angular velocity and acceleration as well. The statistics you see on the left shows the it's both linear and angular velocity and acceleration, it is under the min and max with the third trial having a maximum velocity angular velocity of 20.62, a minimum velocity of 9.192 m/s and a acceleration of 3.198 m/s^2.


Conclusion: After completing the trials we can conclude that our hypothesis was prove correct in regards to the relationship between force and centripetal acceleration. The amount force generated in the trials with the disk attached motor relates to centripetal acceleration. The faster the velocity and acceleration is the higher the force is generated.