course Phy 201 k쏨{ҊbԒ|szׂassignment #004
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21:21:20 How do we reason out the process of determining acceleration from rest given displacement and time duration?
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h肙|ϣP|Ƽo~|[ assignment #003 003. `Query 3 Physics I 05-27-2007
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21:37:57 Query Principles of Physics and General College Physics: Summarize your solution to Problem 1.19 (1.80 m + 142.5 cm + 5.34 `micro m to appropriate # of significant figures)
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RESPONSE --> 1.80 m + 1.4m + 5.34 * 1 m= 1.80 m + 1.4 m + 5.34 m = 1.8 m + 1.4 m + 5. 3 m = 8.5 m I first converted all the numbers to meters, did the correct steps of the order of operations, and then rounded the number to the appropriate number of significant figures which I determined by looking at the initial numbers and determining which had the least specific numbers in terms of significant digits (the 142.5), then I rounded the rest of the numbers to the tenth position since this was the least precise. confidence assessment: 3
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21:40:28 ** 1.80 m has three significant figures (leading zeros don't count, neither to trailing zeros unless there is a decimal point; however zeros which are listed after the decimal point are significant; that's the only way we have of distinguishing, say, 1.80 meter (read to the nearest .01 m, i.e., nearest cm) and 1.000 meter (read to the nearest millimeter). Therefore nothing smaller than .01 m can be distinguished. 142.5 cm is 1.425 m, good to within .001 m. 5.34 * `micro m means 5.34 * 10^-6 m, or .00000534 m, accurate to within .00000001 m. When these are added you get 3.22500534 m; however the 1.80 m is not resolved beyond .01 m so the result is 3.23 m. Remaining figures are meaningless, since the 1.80 m itself could be off by as much as .01 m. **
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RESPONSE --> I am confused. I thought ""um"" is micrometers, which would have thrown off my results. In the explanation to the side, it is used as, well, I am not quite sure. I just figured that 10^5 micrometers is equal to one regular meter, then multiplied by 5.34 is 5.34 meters; then, I added this to the other numbers, giving the answer 8.5. I understand how to do this, I am merely confused about the unit ""um."" self critique assessment: 2
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21:40:41 University Physics #34: Summarize your solution to Problem 1.34 (4 km on line then 3.1 km after 45 deg turn by components, verify by scaled sketch).
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RESPONSE --> I am not in University Physics. confidence assessment:
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21:40:55 ** THE FOLLOWING CORRECT SOLUTION WAS GIVEN BY A STUDENT: The components of vectors A (2.6km in the y direction) and B (4.0km in the x direction) are known. We find the components of vector C(of length 3.1km) by using the sin and cos functions. }Cx was 3.1 km * cos(45 deg) = 2.19. Adding the x component of the second vector, 4.0, we get 6.19km. Cy was 2.19 and i added the 2.6 km y displacement of the first vector to get 4.79. So Rx = 6.19 km and Ry = 4.79 km. To get vector R, i used the pythagorean theorem to get the magnitude of vector R, which was sqrt( (6.29 km)^2 + (4.79 km)^2 ) = 7.3 km. The angle is theta = arctan(Ry / Rx) = arctan(4.79 / 6.19) = 37.7 degrees. **
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RESPONSE --> -- self critique assessment:
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