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Phy 231
Your 'cq_1_13.1' report has been received. Scroll down through the document to see any comments I might have inserted, and my final comment at the end.
** CQ_1_13.1_labelMessages **
A ball rolls off the end of an incline with a vertical velocity of 20 cm/s downward, and a horizontal velocity of 80 cm/s. The ball falls freely to the floor 120 cm below.
For the interval between the end of the ramp and the floor, hat are the ball's initial velocity, displacement and acceleration in the vertical direction?
voy = 20 cm/s
'dy = 120 cm
a = 980 cm/s^2
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What therefore are its final velocity, displacement, change in velocity and average velocity in the vertical direction?
vf = 'sqrt(voy^2 + 2*a*'ds) = 'sqrt((20 cm/s)^2 + 2*980cm/s*120cm) = 485.386 cm/s
vAve = (485.386 cm/s + 20 cm/s) / 2 = 252.693 cm/s
'ds = vave * 'dt, 'dt = 'ds /vave = 120 cm / 252.693 cm/s = .474885 sec
Final awnsers
vf = 490 cm/s
'ds = 180 cm
vave = 250 cm/s
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What are the ball's acceleration and initial velocity in the horizontal direction, and what is the change in clock time, during this interval?
a = 0 cm/s^2
vox = 80 cm/s
'dt = 'dsy = vave * 'dt, 'dt = 'ds /vave = 120 cm / 252.693 cm/s = .474885 sec
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What therefore are its displacement, final velocity, average velocity and change in velocity in the horizontal direction during this interval?
vox ave = (80 cm/s + 80 cm/s) / 2 = 80 cm/s
'ds = vAve * 'dt = 80 cm/s * 0.474885 s = 37.99 cm = 38 cm
vf = vo = 80 cm/s
'dvelocity = 0 cm/s
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After the instant of impact with the floor, can we expect that the ball will be uniformly accelerated?
After impact, i think different materials will have different vaslues of acceleration.
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Why does this analysis stop at the instant of impact with the floor?
analysis stops at the instant of impact because the constant acceleration interval is from free fall to end impact.
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20 mins
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So once a projectile leaves its energy giving system, at that point, there is no more horizontal acceleration except for maybe air resistance?
@&
That is correct.
Good work.
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Task: `q003. You won't fully understand the sequencing of topics and activities, or the reasons for the sequencing, until you have worked through a number of assignments.
Assumptions:
• It is unrealistic to suppose that the majority of students in a course are capable, without prior preparation, of reading, extracting meaning from and solving problems in a text written at a level appropriate to the course.
• having the topic talked to a class in a lecture is generally ineffective for the majority of the class
• students sharing ideas with and solving problems in conjunction with other students can be very helpful, given a group of students who have already engaged and experienced the topic (... toolkits ...)
• it takes time for stuff to sink in, an idea the instructor believes to have for centuries been obvious to individuals with rigorous content knowledge, to now be increasingly supported by the rapidly advancing field of neurobiology, but not to have filtered down to the 'field' of education
• if the goal of the course is integrated understanding and mastery, it is not possible to break the learning of this subject into a linear series of topics, with one topic mastered before moving on to the next
Typically you will be introduced to a topic through a sequenced set of questions (the 'qa'), in which you will
• Answer a series of questions, based on knowledge from prerequisite courses or from earlier in this course, without having been first 'taught' how to answer the questions. The purpose is to 'engage your brain' on the topic and provide you with a context for later activities.
• Solve, take notes on and generally understand a sequenced series of worked-out problems (the Introductory Problem Sets) illustrating the application of the topic, along with others.
• Apply the ideas to one or more actual, hands-on physical systems, typically setting the system up, taking data, analyzing results and answering questions.
• Read Class Notes documents which may address any combination of selected previous, current and future topics, and/or view video-linked versions of the same.
• Read the associated 'material' in the text and solve text problems. The text is the 'last word' on a topic, not the first. By the time you read about the topic in the text, you will already know quite a bit about it through having engaged and experienced it. The text is intended as the final document for the topic, presenting it in clear relation to others.
These activities can span a number of assignments, so that by end of the process the topic will have had time to percolate and sink in.
The main thing you need to understand about this is that there are dozens of topics in your course, each of which can require days or weeks to develop. The result is that at any time you will simultaneously bedeveloping and working on a number of topics.
Again you aren't expected to completely understand the assumptions and the sequencing. However give a short synopsis of what you do understand.
**** Your response (insert your response beginning in the next line; the next line is blank and doesn't include the #$... prompt):
The student needs time for all of the ideas to sink in. Therefore it would be beneficial for the student to read notes, watch videos, and relate to the textbook as the final word.
#$&* (your response should have gone on the line above this one)
*#&!
&#Good responses. Let me know if you have questions. &#