I need help with the worksheet because I keep getting 50% but I'm still confused as to why.
Lab 04 is the last worksheet I did with my teacher's feedback, to give you an idea as to what I'm doing wrong,
Data
| Lab 05 – RDO-01 | ||
| Name: | ||
| Table 1: Acceleration and Angular Velocity for Uniform Circular Motion | ||
| Angular Velocity, ω | Centripetal Acceleration, ac | Angular Velocity Squared, ω2 |
| rad/s | m/s2 | (rad/s)2 |
| G1: a vs. ω | y | x |
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BCIT Department of Physics © Dr. M. Harder
Version: Oct-22 – 1 – © Dr. M. Harder
RDO-01: Rotational Motion – Worksheet
Maximum Score: 13
Part A
1. [2] In uniform circular motion, what is the direction of the linear velocity at each instant? Draw a picture if this helps you explain. Describe how your answer is evident in the video.
2. [2] What is the direction of the centripetal force required for uniform circular motion? Draw a picture if this helps you explain. Describe how your answer is evident in the video.
Part B
3. [2] Attach a graph of ac vs ω2 that is properly plotted, analyzed and labelled. The data should be reasonable and there should be at least 8 data points. If you do not have at least 8 useful data points, explain how you tried to modify your experiment to collect more data and why you think you were unable to collect the required minimum of 8 data points.
4. [1] What did you look for when ensuring your data points made sense? If you excluded any data points, what made you remove those points? What could explain this outlier data?
5. [1] Which model equation did you choose to fit your data? Why? 6. [1] Write out your fit equation for ac vs ω2. 7. [1] Does your experimental result agree with the expected relationship between centripetal
acceleration and angular velocity? Justify your response. 8. [1] What is your value of r? 9. [2] What does this value of the radius physically represent, and is this result reasonable?
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BCIT Department of Physics
Version: Oct-22 – 1 – © Dr. M. Harder
RDO-01: Rotational Motion
Learning Outcomes
In this lab you will improve your ability to:
Follow a definite set of instructions for the collection and analysis of data.
Create and analyze graphs.
Design a simple experiment with a well-defined objective.
Experimental Objectives
The objectives of this experiment are to:
Verify the direction of the velocity and acceleration in uniform circular motion.
Verify the relationship between centripetal acceleration and angular velocity.
Apparatus
• Computer with Excel • Android or iOS smartphone or tablet with “phyphox” by RWTH Aachen University.
Theory
An object moving in uniform circular motion has a constant speed and a velocity that is always tangent to the circular trajectory. Even though the speed is constant, since the velocity vector changes direction the object continually accelerates. This acceleration is produced by an inward unbalanced force called the centripetal force. The centripetal force is not necessarily a single force, but rather the sum of all centre directed forces. If the centripetal force were not present the object could not maintain its circular motion.
An object of mass, 𝑚, moving at a speed, 𝑣, in a circular path of radius, 𝑟, experiences a centripetal acceleration of magnitude:
a! = v"
r (1)
This acceleration is directed toward the centre of the circular orbit and is perpendicular to its path. The constraint in Eq. (1) is in addition to Newton’s laws. Therefore, if we also apply Newton’s second law, the corresponding centripetal force must be given by:
𝐹# = 𝑚$! = 𝑚) 𝑣"
𝑟 * (2)
RDO-01 BCIT Department of Physics
– 2 – © Dr. M. Harder
Since the centripetal acceleration is towards the centre of the circular trajectory, the centripetal force must also point in this direction. 𝐹# is an unbalanced force that may be due to many different sources, such as friction, gravity, electric fields etc.. For example, cars are able to turn a corner because of the sliding friction force between the wheels and the road surface, which provides the necessary centripetal force. If the friction force is insufficient, the car will skid and be unable to make the turn within the radius of curvature of the road.
The linear (or tangential) speed 𝑣 is related to the angular speed ω by the relationship
𝑣 = ω𝑟 (3)
and therefore, when combined with Eq. (1), the centripetal acceleration for an object moving along a circular path of radius 𝑟 may be written as:
𝑎# = 𝑟ω". (4)
Procedure
Part A: The direction of 𝒗00⃗ and 𝒂𝒄0000⃗
Watch the two videos, https://www.youtube.com/watch?v=lNe59oGVLuE and https://www.youtube.com/watch?v=kIsQlbNwtPU, and answer the corresponding questions in the worksheet
Part B: The Relationship between 𝒂𝒄 and ω
1. Download and open the phyphox app by RWTH Aachen University.
2. Scroll down to the Mechanics section and tap Centripetal acceleration.
3. Place your phone on a smooth surface with the screen facing up.
4. Tap the triangular play button to start recording data. Gently spin your phone so that it rotates about its centre.
5. Once the phone has stopped rotating, tap the pause button to stop recording data.
6. To send the data to your computer for analysis: Tap the three vertical dots at the top right corner of the screen and then tap Export Data. Select Excel (this should be selected by default) and then tap OK. Select your preferred method of sharing to your computer (e.g. email, Bluetooth, Google Drive etc.)
BCIT Department of Physics RDO-01
– 3 – © Dr. M. Harder
Data Analysis
Record results into RDO-01.xlsx.
Part B: The Relationship between 𝒂𝒄 and ω
Copy the data you exported from phyphox into the RDO-01.xlsx spreadsheet.
Complete the spreadsheet, calculating ω2.
In GraphIt plot ac (y) as a function of ω2 (x), and fit your data using an appropriate model. If the R2 value exceeds 0.999 you can say that your experimental result agrees with the expected relationship between the centripetal acceleration and the angular velocity. Check your data to ensure you do not have any clear outliers (especially at low or high frequencies). If you do have clear outliers, remove these data points. If you do not have at least 8 useful data points, modify your setup, and run the experiment again.
Worksheet
Complete the RDO-01 worksheet on separate sheets of paper and attach a PDF of your data tables and plot. See Sec. 9 of the lab manual introduction. Submit your PDF to the appropriate Learning Hub Assignment folder.
