Significant figures in seconds to hours calculation

[RossH]

SOLVED: Significant figures in seconds to hours calculation

Homework Statement

Not exactly a problem, but if I have minutes/seconds and am changing to hours, how many significant figures are there? For example: 29 minutes 57 seconds =0.499166667 hours needs ? significant figures.

The Attempt at a Solution

Well, a second to 1/3600 hours. Therefore, I think I might want to measure to a precision of one ten-thousandth of an hour, or possibly 1/1000 hours. I'm not sure which. I know that the minutes doesn't affect the calculation, and I know that the unit conversion is considered to have infinite sig figs.

 

[gneill]

The implication is that the original value is accurate to +/- 1 second. If the converted value is to have a similar level of precision, and 1s = 0.00028 hr, then it looks like you'll want four decimal places and the last place will be taken as +/- 3.

 

[RossH]

The implication is that the original value is accurate to +/- 1 second. If the converted value is to have a similar level of precision, and 1s = 0.00028 hr, then it looks like you'll want four decimal places and the last place will be taken as +/- 3.

Thanks!

 

[Redbelly98]

I agree the value is accurate to the nearest 1 second, but would approach it differently. If you convert the 29 minutes 57 seconds to seconds, that's 60·29+57 seconds or 1767 seconds. That's 4 significant figures -- which for this problem (0.4991... hours) means to the 4th decimal place in agreement with what gneill said.