- #1

BillhB

- 35

- 0

## Homework Statement

Convert ##120. \frac{km}{h}## to ##\frac{m}{s}##

## Homework Equations

##1 km=10^3 m##

##1 hour = 3600 seconds##

## The Attempt at a Solution

Not so much concerned with the solution, it's easy, as to what happened after the solution was found. So you get ##33.33\overline{33}##, after which the professor rounded to 33.3 citing significant figures. That makes no sense though, if we go back in the other direction we would see this new value is actually ##119.88\frac{km}{h}## which is more precise than the original value. If you used this value in another calculation it seems like it would defeat the entire purpose of doing the whole silly significant figure thing in the first place.

Now you could just cite significant figures again and get back to 120., but if you wanted to convert the value into use again at a later date you'd have rounding error. The chemistry lecture professor basically brushed me off when I brought it up. I was arguing that the entire ##33\frac{1}{3}## was significant.

Who's right? Any insights here?