Mr Davis 97
I have a question about sig figs and how they relate to measuring. Say I am finding the velocity of a small object. From an experiment, I gather the data that the object moved .0765 meters in .07 seconds. As one can tell, my watch is less precise than my fancy ruler. Using these data, I calculate the velocity my dividing .0765 m by .07 s. My question is, how many significant figures will the resulting calculation have? I'm sure that it will be 1 significant figure since the time measurement only has one. However, if this is true, would it mean that if I measured the time interval to, say, 1 second, the velocity calculation would have 2 significant figures? Is it true that the longer I measure the time interval, the more precise it will be?

Writing ".07" is a little ambiguous- it is not clear whether that is to have two significant figures or one. Better would be $7.65 \times 10^{-2}$ showing it has three significant figures and either $7 \times 10^{-2}$ or $7.0 \times 10^{-2}$ depending upon how many significant figures you intend. An operation Involving significant figures is no more accurate than the least accurate number.