course Phy 231 ???w????????assignment #004004. `Query 4
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15:36:54 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 --> Since a = (vf - v0) / 'dt, vf = ( a * 'dt) + v0 Once vf is known, ( vf - v0 ) * 'dt = 'ds confidence assessment: 3
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15:38:59 **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 --> OK, I forgot to divide (vf + v0) by 2 before multiplying by 'dt. That was a careless mistake. I also see the different way you went about determining vf. I believe my way would work, but what you presented is more straight-forward. self critique assessment: 2
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15:42:20 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 That is, the final velocity added to the initial velocity, divided by two, gives us the vAve. Multiplying that by the change in clock time gives us the displacement (known as 'ds). confidence assessment: 3
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15:42:33 ** 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 --> OK self critique assessment: 3
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15:44:26 Describe the flow diagram we obtain for the situation in which we know v0, vf and `dt.
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RESPONSE --> If we know v0, vf and 'dt, we can determine both vAve and 'ds. We can also determine acceleration. Given the initial and final velocities, we can easily determine the change in velocity per clock time. confidence assessment: 2
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15:45:47 ** 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 --> OK, I guess I didn't understand the question. It appears you were looking for a ""family tree"" type relationship between the various components of acceleration and velocity. self critique assessment: 2
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15:47:01 Query Add any surprises or insights you experienced as a result of this assignment.
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RESPONSE --> The rotating straw assignment was interesting and informative. Angular velocity was a different spin on the velocity concepts we've been studying thus far. I feel reasonably comfortable with the material. confidence assessment: 3
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15:47:19 ** 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 --> OK self critique assessment: 3
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