Lab deck: Multiple



Lab deck: Multiple

Johann Alcaraz

Mary Regacho

Mariah Barrera

Lab #39: Angular Position vs. Velocity

Purpose

 

 

Apparti

Theory

 

Methods

 

 

 

Analysis

Analysis

 

Conclusions

• To use the Datastudio program to record data and analyze data

• To plot angular position and velocity

• To use the rotary motion sensor to measure the rotation of a disk that undergoes constant angular acceleration .

• to understand the relationship between angular and linear velocity

[pic]

 

Mariah; assigned

Every kinematic quantity has an analogous quantity in rotational kinematics. The rotational version of position is the "angular position". The rotational version of velocity is "angular velocity" that.

The motion of a fan cart accelerating on a flat track is described as translational kinematics.

Angular displacement, angular velocity, and angular acceleration can be brought together to produce a set of equations called the equations of kinematics for constant angular acceleration.

The equations of kinematics for constant angular acceleration can be used for solving problems involving rotational motion..

The lab group followed this provided set of procedures as accurately as they could with a few minor changes in that they repeated a few of the steps. All in all, these procedures were their guides.  

Setup

1. collect materials

2. situate group at lab deck

3. delegate jobs from person to person

4. read through lab packet as a group and formulate a plan of attack

5. Set up the PASCO Interface and computer and start DataStudio.

6. Connect the Rotary Motion Sensor to the interface.

7. Open the DataStudio file: 39 Rotational Motion.ds.

o The DataStudio file has graph displays of Angular Position and Angular Velocity versus Time. The Rotary Motion Sensor is set to record at 20 Hz.

8. Mount the Rotary Motion Sensor on a support rod.

9. Mount the Super Pulley with Table Clamp on the end of the Rotary Motion Sensor.

10. Attach one end of a piece of thread (about 1 m) to the hole in the edge of the medium diameter part of the three-step pulley on the Rotary Motion Sensor.

11. Adjust the Super Pulley and thread so the thread is tangent to the medium pulley.

12. Remove the thumbscrew that holds the three-step pulley onto the sensor. Place the disk of the rotational accessory on the top of the three-step pulley and replace the thumbscrew to hold the disk in place.

13. Attach a mass hanger to the end of the thread. Turn the disk to wind the thread until the mass hanger is almost up to the Super Pulley.

14. Hold the disk until you are ready to record data and measure the rotational motion.

Procedure

When you are ready, click ‘Start’ to begin recording data. Release the disk so it is free to rotate.

Allow the disk to rotate until the string is almost completely unwound. Click ‘Stop’ before the string unwinds all the way.

Click the ‘Scale to fit’ button to rescale the graph if needed.

[pic]

Questions

1. How does the shape of the graph of angular position versus time compare to the graph of linear position versus time?

-Angular position vs. time is curved, but linear position vs. time is linear. 

2. How does the shape of the graph of angular velocity versus time compare to the graph of linear velocity versus time?

- the graph of angular position was a curved graph, while the graph of linear position was linear.

3. What are possible sources of error in this activity?

- The possible sources of error in this activity are the first of all human error. We did this lab in less than 10 minutes, so there is a high possibility that we might have missed something as a group. Another source of error could be the limitations of the equipment used.

4. Linear acceleration is determined by the ratio of the net force on an object to the mass of the object. Based on this exploration, do you think there is a similar ratio that determines the angular acceleration of a rotating object?

• Yes, this ratio probably has the same concept of force over mass to get acceleration. This relationship could probably be seen by the equation FR=MaR=Mv2/r you would just need to manipulate the equation to get acceleration.

JOHANN'S CONCLUSION

Results

    From the data, we can conclude that the graph of angular velocity vs. time is an apparent derivative of the angular position vs, time graph. This is seen by the type of graph plotted with velocity being linear and position being parabolic. It is also seen that velocity is increasing at a constant rate.   

 

Purposes

1. To use the Datastudio program to record data and analyze data

- The recording was easily accomplished through doing the lab procedures but the analyzation of the data did not get anywhere; Mary and I both found the analyzation difficult and just took it as it came through our knowledge of graphs and relationships.

2. To plot angular position and velocity

- Data Studio automatically fulfilled this purpose for us.

3. To use the rotary motion sensor to measure the rotation of a disk that undergoes constant angular acceleration

- Again, this was basically a no-brainer fulfilled by bascially just doing the lab, or in this case, watching Raymond do the lab.

4. To understand the relationship between angular and linear velocity.   

- From this lab, I really don't understand it. I did not accomplish this purpose through this lab.

 

Knowledge

    Frankly, these labs weren't very helpful to me. My lack of preparation surely was one of the factors why but other reasons came into play as well. Perhaps the calss failed to participate in Socratic dialogue agauin which reuslted in these set of labs. In my opinion, three, four, or five labs at once isn't working very well. Even if the lab reports are due 5 days later. 

    I may not have much knowledge to contribute in this conclusion but I think it's apparent that I did not comprehend much. However, what I do have to offer is an alternative way to complete this arrangement  of labs. Instead of having a variety of labs at differnet stations, and having griups alternate bewteen lab decks. How about, each group does the same lab at their own lab deck on the same day. That way, they dont have to worry about getting to other labs. Each group will be able to complete the lab on the same day, and perhaps allow for more group communication and sharing of results. As for the lab write-ups, rather than it being all due collectively on one day, the lab would be reasonably due 2 days later. So basically, all groups do a lab on Monday, and the write up due Wednesday night. With this, 4 labs can be accomplished in 1 week, but in a more orderly fashion and allow for less "stress" and more collaboration and thought process. 

    This may not be the cutomary conclusion, but I believe I've put in my two cents and given what knowledge I do have of the situation. As much time as you have spent preparing those templates for us (which I thank you), I dont think that was the best way to minimize our time spent on the lab write-ups. To me, it just allowed more shortcuts and therefore allowing laziness to seep in. In the process of writing up labs, typing up the procedures as the group specifically did them, retyping the background information or theory in our own words, and such, played a crucial role in my development of understanding. I think that is why I did much better on the latter set of 5 labs (Newton's Laws) compared to this.

 

Mary’s conclusion

Results

•                The data collected shows that angular velocity is the derivative of angular position.  This relates to the concept in translational motion where the velocity of an object would be a derivative of the positional graph.  The differences between the two types of motion is that displacement in rotational motion would be represented in angles.

 

Purposes

•                The first purpose was completed by utilizing the Datastudio program and sensors to record the data.  Using the Datastudio program also enabled us to plot the angular position and velocity.  And this also accomplishes our third purpose of using the rotary motion sensor to detect the constant accelerating motion.  The equipment used helped us to plot angular position and velocity.

•                The fourth purpose was fulfilled when my partners and I looked at the graphs analyzed the graphs in order to answer the questions.

•                Finally, the fifth purpose of the lab was fulfilled by answering the questions the lab gave us.  The questions in the lab hinted at a connection between rotational motion and linear motion by using the concept of Newton’s second law and using ratios.  We could relate the two ideas together with our previous knowledge of manipulating Newton’s second law.  Then the questions kept hinting at a relationship between the graphs of velocity and position and this went back to our knowledge of the graphs of linear motion.  How the graphs of velocity was a derivative of position, and acceleration a derivative of velocity.

 

Knowledge

            Trying to understand angular motion from Giancoli was a real challenge.  I could barely grasp any concepts.  it was difficult coming into the lab with my limited knowledge of circular motion.  I feel the pace is really hard to keep up to.  These labs would have been a lot easier if we had a stronger back round with circular motion.  After seeing the data from the lab and answering the questions I began to get a much better understanding of the chapter.  I finally understood how, rotationally, the angle is the same thing as the displacement in linear motion.  And how all linear motion has counterparts in rotational motion.  If my partners and I had more time on the lab we would try to change the variables with velocity, radius, and mass.  It would be interesting to predict what would happen If we were to change those variables.  Conducting more trails would also be a part of our list to do.  Understanding where the fluctuations in our graph occurred and why would be a big help to making our data much more precise and accurate.  If we had more time we would try and figure out how these fluctuations came to be.

Mariah's Conclusion

Results: The graph shows that velocity plays a key role in the derivative position. Translational and rotational also is seen on the graph.

Purposes:Plotting the velocity and angular positions using the help of datastudio. The rotary motion sensor was used to plot these points on our graph. The questions were the last of the purposes but I found this the most difficult because I'm still unsure of myself.

Knowledge: This lab was a little simpler and somewhat easier to follow because observing helps me follow things more easily. I'm still unsure of myself answering questions because I'm still not sure of how to answer questions or even where to start. I feel doing more labs will help this become easier for me and the help of my Johann and Mary also lifted the difficulty level.

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