Physics 1xx Laboratories_ Rounding errors

Physics 1xx Laboratories_ Rounding errors - Physics 1xx...

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Physics 1xx Laboratories - Web Assign Rounding Errors, or, Why Won't WebAssign Accept My Answer? Here is a common complaint: "I know I am doing the problem correctly, but Webassign won't accept my answer, no matter how many significant figures I try. .. " Under the assumption that the student is really doing the problem in the correct way, what could the reason be that the answer is not being accepted? Answer: ROUNDING ERRORS . Rounding errors tend to creep into multi-part problems when one result early in the problem is used to calculate another result later, and the student uses the submitted number (which is rounded) in the later calculation. However, it can be tricky to determine which number has been rounded "too much". This is because the criterion for acceptibility for a given submission slot is based on the percent difference between the key and the submission, and a given percent of a small number is much less than the same percent of a larger number. For example, assume that the problem requests a value and an uncertainty, e.g., g = ± m/s 2 If the value is 9.81 m/s 2 and the uncertainty is 0.03 m/s 2 , and both are required to be within 2% of the correct value, then 9.62 to 10.00 would be accepted for the first value, but only 0.0294 to 0.0306 would be accepted for the second value. Note, in particular, that 0.029 and
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This note was uploaded on 01/20/2012 for the course PHYSICS 118 taught by Professor Jensgundlach during the Winter '12 term at University of Washington.

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Physics 1xx Laboratories_ Rounding errors - Physics 1xx...

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