Cuesta College, San Luis Obispo, CA
Students have a bi-weekly online reading assignment (hosted by SurveyMonkey.com), where they answer questions based on reading their textbook, material covered in previous lectures, opinion questions, and/or asking (anonymous) questions or making (anonymous) comments. Full credit is given for completing the online reading assignment before next week's lecture, regardless if whether their answers are correct/incorrect. Selected results/questions/comments are addressed by the instructor at the start of the following lecture.
The following questions were asked on reading textbook chapters and previewing a presentation on forces and motion.
Selected/edited responses are given below.
Describe what you understand from the assigned textbook reading or presentation preview. Your description (2-3 sentences) should specifically demonstrate your level of understanding.
"In the absence of any other forces, an object will maintain a constant velocity, whether that velocity has a non-zero or zero magnitude."
"The purpose of a net force acting on an object is not to sustain the object's velocity, but rather, to alter it. Therefore, having a velocity of zero is equivalent to any constant velocity."
"Newton's first law of motion states that the velocity of an object will remain constant or at rest until an external force acts on it to change its motion. Newton's second law of motion states that net force is directly proportional to mass and acceleration."
"In Newton's first law, an object's velocity vector remains constant if and only if the net force acting on the object is zero. However, if the speed and the direction were not constant, it applies to Newton's second law."
"There are only two ways of classifying motion; motion is classified as constant or changing. We use Newton's first and second law, respectively, to describe these motions."
Describe what you found confusing from the assigned textbook reading or presentation preview. Your description (2-3 sentences) should specifically identify the concept(s) that you do not understand.
"I read the concepts but I'm not sure I'm fully understanding the difference between Newton's first and second laws."
"Will definitely need practice problems to be shown in class for applications of Newton's laws."
"I think I took enough time to understand what I read, now I just need to apply it to make things clearer. But now I take that back--I thought I understood until I tried to answer the questions below."
"I am confused about forces 'canceling' and how Newton's laws apply to either zero net force or non-zero net force. I also am not sure how to apply it to specific situations, like whether uniform circular motion is considered constant. I vaguely understand which concept is paired with which and the basic steps for determining first/second law and zero/non-zero net forces, but I don't fully understand why (other than because the flowcharts say so)."
Identify whether a zero or non-zero net force corresponds to Newton's first law or Newton's second law. (Only correct responses shown.)
Zero net force (ΣF = 0): Newton's first law ("N1") [86%]
Non-zero net force (ΣF ≠ 0): Newton's second law ("N2") [86%]
For the rocket sled, Newton's __________ law applies to the motion of this object, and the forces acting on the object add up to a __________ net force.
first; zero. ********************* [21] second; non-zero. **************************************** [40] (Unsure/guessing/lost/help!) ** [2]
While the F-35B is descending (before it touches the ground), Newton's __________ law applies to the motion of this object, and the forces acting on the object add up to a __________ net force.
first; zero. ************************************ [36] second; non-zero. ********************** [22] (Unsure/guessing/lost/help!) ***** [5]
For this car with a steady speedometer reading (and assuming the shaking is due to the person holding camera, and not from moving the car itself), Newton's __________ law applies to the motion of this object, and the forces acting on the object add up to a __________ net force.
first; zero. ********************************************* [45] second; non-zero. ************** [14] (Unsure/guessing/lost/help!) **** [4]
For a person in the swinging chair ride moving along a circular trajectory at a constant speed, Newton's __________ law applies to the motion of this object, and the forces acting on the object add up to a __________ net force.
first; zero. *************************** [27] second; non-zero. ******************************* [31] (Unsure/guessing/lost/help!) ***** [5]
For this car with a zero speedometer reading, Newton's __________ law applies to the motion of this object, and the forces acting on the object add up to a __________ net force.
first; zero. **************************************************** [52] second; non-zero. ******* [7] (Unsure/guessing/lost/help!) **** [4]
Ask the instructor an anonymous question, or make a comment. Selected questions/comments may be discussed in class.
"Using the flowcharts helped clarify which Newton's law to use for each motion example."
"I really think that during class, when we use flashcards, that when you bring up a new topic and people are obviously struggling with it that you should provide a lot more 'hand holding.' Show us how to apply this topic to a problem, don't let us sit frustrated and clueless surrounded by other frustrated and clueless classmates." (I only move on to a new topic when the majority of the class displays the correct answer on the flashcards, which I assume they show because (a) they are certain that it is the correct answer, and (b) can explain why that is the correct answer. If you (a) aren't certain that an answer is correct, and/or (b) can't explain why an answer is correct, then pick the "Unsure/lost/guessing/help!" choice. If a sizable portion of the class selects the "Unsure/lost/guessing/help!" choice, then yes, I'll spend more time on class-wide intervention. Otherwise ask questions while I'm circulating during group work in class, come in to office hours, or e-mail me. I'll be sure to address this during class in order for flashcards to give me better feedback not just on whether everyone knows the correct answer, but on gauging the confidence of everyone's understanding.)
"We should have an answer key to the worksheet questions to help assist whether or not we're getting the answers right." (As a matter of policy the answers to the worksheet questions are not published. However, you are free to ask questions while I'm circulating during group work in class, come in to office hours, or e-mail me your answers, and I can "grade" them for you. Just don't wait until the last-minute to do so.)
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