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 work and energy.
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.
"Even if a force is acting on an object, the work done on that object will be zero if it is not moved. Work is computed using the part of the force acting in the direction of movement."
"Work acting on an object increases its translational kinetic energy and that work acting against it reduces the translational kinetic energy."
"Translational kinetic energy is measured in joules. Work results in the change of translational kinetic energy."
"Work is accomplished by exerting a force over a displacement. Work can be done on or against any mechanical energy form or forms."
"How changes in kinetic energy relates to work, and how forces can do work on an object rather than just result in a net force."
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 honestly feel very good about these concepts, and don't currently don't feel confused on the reading."
"I get this sections and its concepts. What I don't understand is where, and how the work-energy theormen was derived."
"The concept of 'work.' I don't understand the concept of it and how to quantitatively describe 'work.'"
Explain how the SI (Système International) unit for work is related to the SI unit for force.
"The units are related by a ratio of one-to-one."
"They are both joules."
"The unit of work is the unit of force times the unit of distance."
"A newton·meter = joule."
Match the description of the work exerted by these forces for each object. (Only correct responses shown.)
Pushing in the same direction of motion: work done "on" the object (positive work). [88%]
Pushing opposite the direction of motion: work done "against" the object (negative work). [93%]
Pushing 90° sideways to the direction of motion: no work done. [57%]
Pulling such that the angle between the force and motion is an acute angle (between 0° and 90°): work done "on" the object (positive work). [58%]
Pulling such that the angle between the force and motion is an obtuse angle (between 90° and 180°): work done "against" the object (negative work). [52%]
on; increases. ********************************************************* [57] against; decreases. ********** [10] (Unsure/lost/guessing/help!) [0]
on; increases. ***** [5] against; decreases. ************************************************************** [62] (Unsure/lost/guessing/help!) [0]
on; on. *** [3] on; against. **************************************************** [52] against; on. ***** [5] against; against. *** [3] (Unsure/lost/guessing/help!) **** [4]
For Mrs. P-dog's translational kinetic energy to be increased while being catapulted, the amount of work from the bungee cords must be __________ the amount of work from the weight force.
less than. * [1] the same as. *** [3] greater than. ************************************************************** [62] (Not enough information is given.) [0] (Unsure/lost/guessing/help!) * [1]
Ask the instructor an anonymous question, or make a comment. Selected questions/comments may be discussed in class.
"Was that your squirrel catapult?" (I wish it was. #squadgoals)
"Hmm....I didn't know I had to answer this portion of the reading assignment to get full credit!" (Eh, not really. Unless you left every other free-response part of the reading assignment blank.)
"How do I determine whether the work done on an object is positive or negative just by knowing the angle between the force and displacements on that object?" (We'll cover this briefly at the start of tomorrow's class.)
"This stuff only gets harder." (Really? After the first midterm each of these chapters is more self-contained, and thus does not critically depend on previous chapters. #ymmv)
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