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course PHY 121
2/2/12 11:00 AM
Answer the following:Which is longer, one cm_d or one cm_s?
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One cm_d
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Which is longer, one cm_s or two cm_t?
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One cm_s
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It is likely that your answers to the following will be in the form of decimal numbers. Give your results to three significant figures:
How many cm_t make a cm?
2.25
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How many cm_t would a measurement of 3 cm be?
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6.65
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How many cm would a measurement of 13 cm_t be?
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5.95
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Does it depend on where on the ruler the measurement is made?
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yes
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How many cm_s make a cm_t?
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0.50.
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How many cm_s would a measurement of 5 cm_d be?
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.75
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How many cm_d would a measurement of 11 cm_t be?
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.8
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Does it depend on where on the ruler the measurement is made?
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yes
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Now answer the following questions about significant figures, including a brief but concise explanation.
Do you think all the significant figures in your result are appropriate? Explain.
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No, due to imperfections in printing and an inability to get precise measurements when aligning the paper, the significant figures cannot be as accurate a 3 significant figures
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To how many significant figures are you pretty sure you could answer these questions. Explain.
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I believe no more than 2 for most measurements would be appropriate
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What is the smallest number of significant figures for which the last figure would be completely meaningless? Explain
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I think a third significant figure would mean little, particularly on the double and triple reduced rulers.
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If you carefully measure the width of an 8.5 x 11 inch piece of paper with an accurate ruler, you are likely to get 21.6 cm. If not you will be within .1 cm of that measurement.
That is 3-significant-figure accuracy. So this level of accuracy can be achieved with a regular ruler.
If you use a ruler to measure something of length 2.3 cm, then while you might be able to estimate the measurement more accurately than that you probably can't claim 3-significant-figure accuracy, because you aren't that accurate at estimating tenths of a centimeter. So in this case you probably can't claim 3-significant-figure accuracy
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In any case, good work.
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