course Phy 121 ]ќRDZ w[assignment #004
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14:40:00 Intro Prob 6 given init vel, accel, `dt find final vel, dist If initial velocity is v0, acceleration is a and time interval is `dt, then in symbols what are the final velocity vf and the displacement `ds?
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RESPONSE --> vf = v0 + a'dt Multiplying the acceleration by the time will give you the final velocity 'ds = vAve * 'dt To find the average velocity, you would take the final velocity that you found above and subtract it from the the initial velocity (v0) and divide it by 2. Once you know that, you already have 'dt. confidence assessment: 2
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14:40:54 **You would use accel. and `dt to find `dv: a * `dt = `dv. Adding `dv to initial vel. vo you get final vel. Then average initial vel. and final vel. to get ave. vel.: (v0 + vf) / 2 = ave. vel. You would then multiply ave. vel. and `dt together to get the distance. For example if a = 3 m/s^2, `dt = 5 s and v0 = 3 m/s: 3 m/s^2 * 5 s = 15 m/s = `dv 15 m/s + 3 m/s = 18 m/s = fin. vel. (18 m/s + 3 m/s) / 2 = 10.5 m/s = vAve 10.5 m/s * 5 s = 52.5 m = dist. In more abbreviated form: a * `dt = `dv v0 + `dv = vf (vf + v0) /2 = vAve vAve * `dt = `ds so `ds = (vf + v0) / 2 * `dt. **
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RESPONSE --> i think that's what i said. self critique assessment: 2
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14:43:21 What is the displacement `ds associated with uniform acceleration from velocity v0 to velocity vf in clock time `dt?
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RESPONSE --> 'ds = (vf - v0)/2 * 'dt confidence assessment: 1
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14:43:36 ** Since accel is uniform vAve = (v0 + vf) / 2. Thus displacement is `ds = vAve * `dt = (v0 + vf) / 2 * `dt, which is the first equation of uniformly accelerated motion. **
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RESPONSE --> yeah self critique assessment: 2
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14:52:09 Describe the flow diagram we obtain for the situation in which we know v0, vf and `dt.
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RESPONSE --> The known variables will be lined on the first row of the diagram. v0, vf, and 'dt. Lines would be drawn from each known variable and come together to form another variable. For example, by knowing v0 and vf, we could find the vAve as (vf-v0)/2. By knowing vAve and 'dt, you could find the acceleration. On the graph, there would be a line from 'dt and vAve that would meet at a for acceleration. Lastly by knowing 'dt and vAve, you can figure out the displacement. confidence assessment: 1
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14:52:41 ** The first level in the diagram would contain `dt, v0 and vf. Then v0 and vf would connect to `dv in the second level. The second level would also contain vAve, connected from vf in the first level to v0 in the first level. The third level would contain an a, connected to `dv in the second level and `dt in the first level. The third level would also contain `ds, connected to vAve in the fourth level and `dt in the first level. **
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RESPONSE --> i think i got it. self critique assessment: 2
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14:53:24 Query Add any surprises or insights you experienced as a result of this assignment.
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RESPONSE --> I've suprisingly started to understand this stuff. It's still confusing, but I have a better grasp on it. confidence assessment: 2
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14:53:50 ** Student Response: I think I really confused what information stood for what in the Force and Pendulum Experiment. However, I enjoy doing the flow diagrams. They make you think in a different way than you are used to. INSTRUCTOR NOTE: These diagrams are valuable for most people. Not all--it depends on learning style--but most. **
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RESPONSE --> Flow diagrams help to keep things straight. self critique assessment: 2
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