Two-way vector

Photoshop Phriday: Signs Of Our Times II, by occamsmonkey
somethingawful.com
August 3, 2007

Maybe it's a tensor.

Kudos: from Physics 5A students, Spring Semester 2008

"Sorry I wasn't a more responsible student" by Student 2012
Physics 5A
May 2008
Cuesta College, San Luis Obispo, CA


"I understand the amount of work necessary" by Student 2880
Physics 5A
May 2008
Cuesta College, San Luis Obispo, CA

Kudos: from Astronomy 10 students, Spring Semester 2008

"...But was interested always" by Student 5352
Astronomy 10
May 2008
Cuesta College, San Luis Obispo, CA


"See you next semester" by Student 3512
Astronomy 10
May 2008
Cuesta College, San Luis Obispo, CA

The end of time

Sinfest, by Tatsuya Ishida
www.sinfest.net
September 17, 2007 (excerpt)

Now entering Zeno's Paradox

Photoshop Phriday: Signs Of Our Times II, by Hellkind
somethingawful.com
August 3, 2007

And yet somehow the jaywalker will reach the side of the road.

Education research: feedback on clickers (Cuesta College, Spring Semester 2008)

During Spring semester 2008, Cuesta College students taking Physics 5A (college physics, algebra-based, mandatory adjunct laboratory) at Cuesta College, San Luis Obispo, CA used numerical keypad clickers (Classroom Performance System, einstruction.com) to enter homework and to engage in peer-interaction discussion questions during lecture.

During the last week of instruction, students were given the opportunity to evaluate the instructional components of the course, and the use of clickers in an online "Learning Resource Survey" hosted by SurveyMonkey.com. Questions from section II are adapted from the Student Assessment of Learning Gains (SALG) survey (developed by Elaine Seymour, Wisconsin Center for Education Research, University of Wisconsin-Madison), and questions from section III (III.1, III.3, III.5, and III.7) were adapted from a "Clicker Attitude Survey" (N. W. Reay, Lei Bao, and Pengfei Li, Physics Education Research Group, Ohio State University).

These are the complete survey results, with some preliminary commentary. No statistical analysis was done (this was the first and only administration of this instrument), but will be forthcoming after more data has been compiled from future semesters. Values for the mean and standard deviations are given next to the modal response category for each question. Note that the order of questions within sections II and III were randomly scrambled for each student.

Learning Resource Survey
Cuesta College
Physics 5A Spring Semester 2008 sections 4987, 4988
(N = 28)

I. In order to receive credit for completing this survey, 
   first enter your four digit ID number below:
   ____


II. How much did each of the following aspects of the class help 
    your learning?

II.1 Lecture by instructor.
1. Strongly disagree      0 : 
2. Disagree               5 : *****
3. Neutral                6 : ******
4. Agree                 16 : ****************  [4.0 +/- 0.7]
5. Strongly agree         6 : ******
     
II.2 Doing assigned homework, to be entered using clickers. 
1. Strongly disagree      1 : *
2. Disagree               2 : **
3. Neutral                2 : **
4. Agree                 14 : **************  [4.0 +/- 1.0]
5. Strongly agree         9 : *********

II.3 Doing unassigned homework.
1. Strongly disagree      3 : ***
2. Disagree               1 : *
3. Neutral                8 : ********
4. Agree                 11 : ***********  [3.5 +/- 1.2]
5. Strongly agree         5 : *****

II.4 Using clickers to participate in class. 
1. Strongly disagree      0 : 
2. Disagree               2 : **
3. Neutral                3 : ***
4. Agree                 15 : ***************  [4.0 +/- 0.9]
5. Strongly agree         8 : ********

II.5 Reading the textbook.     
1. Strongly disagree      2 : **
2. Disagree               5 : *****
3. Neutral                4 : ****  [3.4 +/- 1.2]
4. Agree                 13 : *************
5. Strongly agree         4 : ****

II.6 Demonstrations/videos in class.      
1. Strongly disagree      0 : 
2. Disagree               2 : **
3. Neutral                0 : 
4. Agree                 21 : *********************  [4.0 +/- 0.7]
5. Strongly agree         5 : *****

II.7 Interacting with other students during class.   
1. Strongly disagree      0 : 
2. Disagree               0 : 
3. Neutral                7 : ******* 
4. Agree                 16 : **********  [3.9 +/- 0.7]
5. Strongly agree         5 : *****

II.8 Interacting with other students outside of class.
1. Strongly disagree      0 : 
2. Disagree               3 : ***
3. Neutral                7 : ******* 
4. Agree                 11 : ***********  [3.9 +/- 0.9]
5. Strongly agree         7 : *******

Students rated the usefulness of learning by using clickers in class (II.4), more so than any other instructional mode except for demonstrations/videos in class (II.6). Students rated doing assigned homework that was entered using clickers third highest in terms of learning usefulness, more so than lecturing by the instructor (II.1), reading the textbook (II.5), doing unassigned (but suggested) homework (II.3), and interacting with students outside (II.8) and during (II.7) class.

III. Answer the following statements which may or may not describe 
     your beliefs about the use of clickers in this class.

III.1 I like using clickers. 
1. Strongly disagree      1 : *
2. Disagree               3 : ***
3. Neutral                2 : **
4. Agree                 18 : ******************  [3.7 +/- 1.0]
5. Strongly agree         4 : ****

III.2 Clickers helped me understand lectures better.   
1. Strongly disagree      1 : *
2. Disagree               3 : ***
3. Neutral                9 : *********
4. Agree                 12 : ************  [3.5 +/- 1.0]
5. Strongly agree         3 : ***

III.3 I would recommend using clickers in future semesters of Physics 5A. 
1. Strongly disagree      2 : **
2. Disagree               2 : **
3. Neutral                1 : *
4. Agree                 17 : *****************  [3.8 +/- 1.1]
5. Strongly agree         6 : ******

III.4 I will avoid other classes using clickers in future semesters. 
1. Strongly disagree      8 : ********
2. Disagree              14 : **************  [2.0 +/- 0.9]
3. Neutral                4 : ****
4. Agree                  2 : **
5. Strongly agree         0 : 

III.5 Clickers were a positive experience.    
1. Strongly disagree      0 : 
2. Disagree               2 : **
3. Neutral                6 : ******
4. Agree                 16 : ****************  [3.8 +/- 0.8]
5. Strongly agree         4 : ****

III.6 Too much time in class was spent using clickers.   
1. Strongly disagree      2 : **
2. Disagree              16 : ****************  [2.4 +/- 0.9]
3. Neutral                6 : ******
4. Agree                  3 : ***
5. Strongly agree         1 : *

III.7 Too many clicker questions were asked. 
1. Strongly disagree      4 : ****
2. Disagree              16 : ****************  [2.3 +/- 1.0]
3. Neutral                4 : ****
4. Agree                  3 : ***
5. Strongly agree         1 : *
     
III.8 Clickers should be used to collect assigned homework. 
1. Strongly disagree      2 : **
2. Disagree               3 : ***
3. Neutral                5 : *****
4. Agree                 12 : ************  [3.6 +/- 1.2]
5. Strongly agree         6 : ******
     
III.9 Using clickers was difficult. 
1. Strongly disagree     11 : ***********
2. Disagree              13 : *************  [1.8 +/- 0.9]
3. Neutral                2 : **
4. Agree                  2 : **
5. Strongly agree         0 :

Overall, the responses in section III are positive towards the use of clickers. Although students collectively approved of the use of clickers to collect homework, a vocal minority expressed their comments below.

IV. (Optional.) Please type in any comments you may have regarding 
    the use of clickers in Physics 5A.

The following are all of the student responses to this question, verbatim and unedited.

"the clikers were very useful and i really like how their was alot of participation clicker questions. it helped out understanding the material and becuase of the clikers i felt that i was involved in the class more than other classes."

"I think that the clickers helped me to stay on the same page as the lectures. The clicker question were a good way to keep the students paying attention to the lectures."

"at first, they seemed like a pain. But after a couple of weeks using them, i realized how nice they were. I sat in the back most of the time, and it saved a lot time not having to get up to turn stuff in. sometimes it was frustrating not being able to join in a session after it had started, but that is the only draw back i see with the product."

"I like how they require you to interact with the current discussions in class. However, there are sometimes when I feel we spent too much time with them... and would have been better off seeing another example worked out on the board."

"I feel like too much time was spent using the clickers. While they might have their place for entering homework, I think we could have done more example problems and gotten more material covered with better notes had the clickers not been used."

"it sucks that when we turn in homework we dont get any partial credit or we never find out where we went wrong."

"Have a great summer P-Dog, hope to run into you in the future. 'Enjoy using clickers in your future classes.' (<- To be relevent to clickers.)"

"i still think they cost more than they are worth..."

"Clickers worked well and kept the entire class concentrated on the lecture. Clickers are also a great way to earn some participation points;)"

"We just need to focus our time on the problems, and anwering questions more effieciently and doing problem after problem until we understand"

"The only thing I don't like about the Clickers is the fact that they souldn't be used to colletct homework. I did not like the fact of spending anywhere from a half an hour to an hour on the assigned homework and not getting the correct answer after entering it with the clickers. I believe homework should have been collected by hand for partial credit for showing work. On the contrary, I enjoyed using the clickers for participation credit."

"Thanks for a great class!"

Previous posts:

• Education research: feedback on clickers (Cuesta College, Spring Semester 2008)
  Discussion of end-of-semester student opinions from the start of this past semester.
• Education research: feedback on clickers (Cuesta College, Spring Semester 2008)
  Discussion of preliminary student opinions from the start of this past semester.
• Education research: feedback on clickers (Cuesta College, Fall Semester 2007)
  Discussion of end-of-semester student opinions from a previous semester.

Education research: preliminary MPEX comparison (Cuesta College, Spring Semester 2008)

The Maryland Physics Expectations survey (MPEX) was administered to Cuesta College Physics 5A (college physics, algebra-based, mandatory adjunct laboratory) students at Cuesta College, San Luis Obispo, CA. The MPEX was given during the first week of the semester, and then on the last week of the semester, to quantify student attitudes, beliefs, and assumptions about physics using six question categories, rating responses as either favorable or unfavorable towards:

1. Independence--beliefs about learning physics--whether it means receiving information or involves an active process of reconstructing one's own understanding;
   
2. Coherence--beliefs about the structure of physics knowledge--as a collection of isolated pieces or as a single coherent system;
   
3. Concepts--beliefs about the content of physics knowledge--as formulas or as concepts that underlie the formulas;
   
4. Reality Link--beliefs about the connection between physics and reality--whether physics is unrelated to experiences outside the classroom or whether it is useful to think about them together;
   
5. Math Link--beliefs about the role of mathematics in learning physics--whether the mathematical;
   formalism is used as a way of representing information about physical phenomena or mathematics is just used to calculate numbers;
   
6. Effort--beliefs about the kind of activities and work necessary to make sense out of physics--whether they expect to think carefully and evaluate what they are doing based on available materials and feedback or not.

Cuesta College
Physics 5A Spring Semester 2008 sections 4987, 4988
(N = 29, matched pairs)
Percentage of favorable:unfavorable responses
        Overall Indep.  Coher.  Concept Real.   Math    Effort
Initial 55:17   44:13   41:27   52:19   76:05   52:14   68:10
Final   48:29   37:29   43:36   54:30   70:10   42:30   44:33

Previous posts:

• Education research: preliminary MPEX comparison (Cuesta College, Fall Semester 2007)
  (More detailed discussion on interpreting historical MPEX results at Cuesta College.)
  
• Education research: student expectations in physics
  (Background on the MPEX by E. F. Redish, J. M. Saul, and R. N. Steinberg.)

Rearview train

Rearview Train, by pvictory
Worth1000.com
Amazing Reflections and Shadows contest

1. The train may appear closer than it actually is.
2. A perfectly inelastic collision is imminent.

Physics final exam question: hot coffee plus frozen coffee

Physics 5A Final Exam, Spring Semester 2008
Cuesta College, San Luis Obispo, CA

Cf. Giambattista/Richardson/Richardson, Physics, 1/e, Problem 14.40

[20 points.] A Physics 5A student is going to make iced coffee by first brewing hot coffee, at a temperature of 85.0° C, and pouring it into a glass containing 0.300 kg of frozen coffee from a freezer at –15.0° C. How much hot coffee should the student pour into the glass, in order to result in a final temperature of 10.0° C? Assume that coffee is essentially water. Neglect the temperature change of the glass. Show your work and explain your reasoning.

(The specific heat of ice is 2.10 kJ/(kg*K); the specific heat of water is 4.19 kJ/(kg*K); the latent heat of fusion for water is 334 kJ/kg.)

Solution and grading rubric:

• p = 20/20:
  Correct. Net heat exchange with the environment (or glass) is set to zero, and equates this to sum of the heat taken in by the ice to warm up from -15.0 degrees C to 0 degrees C, the heat taken in to melt this ice completely, the heat taken in by the melted ice (as water) to warm up from 0 degrees C to 10 degrees C, and the heat given up by the coffee to cool down from 85.0 degrees C to 10.0 degrees C. Solves for the mass of the hot coffee, which is 0.389 kg.
  
• r = 16/20:
  Nearly correct, but includes minor math errors. May neglect the specific heat capacity for ice and water being different, or may have converted temperature changes in Celsius into absolute temperatures in Kelvins.
  
• t = 12/20:
  Nearly correct, but approach has conceptual errors, and/or major/compounded math errors. At least has energy balance equation with systematic application of Q = m*c*delta(T) and Q = m*L heat exchanges.
  
• v = 8/20:
  Implementation of right ideas, but in an inconsistent, incomplete, or unorganized manner.
  
• x = 4/20:
  Implementation of ideas, but credit given for effort rather than merit.
  
• y = 2/20:
  Irrelevant discussion/effectively blank.
  
• z = 0/20:
  Blank.
  

Grading distribution:
p: 3 students
r: 3 students
t: 10 students
v: 15 students
x: 0 students
y: 1 student
z: 0 students

A sample of a "p" response (from student 1484) is shown below:
An "r" response (from student 7937) that uses the same heat capacity for ice and for liquid coffee:
An "x" response (from student 1337) that ends on a friendly note:

Physics final exam question: cable, boom, and load

Physics 5A Final Exam, spring semester 2008
Cuesta College, San Luis Obispo, CA

Cf. Giambattista/Richardson/Richardson, Physics, 1/e, Problem 8.37

[20 points.] A uniform beam and sign are suspended using a cable that has a breaking strength of 200.0 N, as shown at right. The sign has a weight of 150.0 N and the beam's weight is 60.0 N. The beam's length is 2.00 m and the sign is a square 1.00 m on each side. What is the minimum angle theta allowed between the beam and cable? Show your work and explain your reasoning.

Solution and grading rubric:

• p = 20/20:
  Correct. In order for the beam and sign to be suspended, the net torque on this system must be zero, and equates this to the sum of the torques of the weight of the beam and sign, and the torque of the cable (using the left end of the beam as the origin). Solves for the minimum angle allowed, which is 45.4 degrees.
  
• r = 16/20:
  Nearly correct, but includes minor math errors. May have mismeasured a lever arm.
  
• t = 12/20:
  Nearly correct, but approach has conceptual errors, and/or major/compounded math errors. At least has net torque equation set to zero, but problematic calculation of individual torques.
  
• v = 8/20:
  Implementation of right ideas, but in an inconsistent, incomplete, or unorganized manner. Some systematic approach at calculating individual torque terms.
  
• x = 4/20:
  Implementation of ideas, but credit given for effort rather than merit.
  
• y = 2/20:
  Irrelevant discussion/effectively blank.
  
• z = 0/20:
  Blank.
  

Grading distribution:
p: 4 students
r: 7 students
t: 3 students
v: 12 students
x: 2 students
y: 1 student
z: 2 students

A sample of a "p" response (from student 1468) that keeps it short and simple is shown below:
An "r" response (from student 6867) with an error in a lever arm:
A rather flippant "x" response (from student 1337):