You could align the edge of the object with the zero on the ruler and then read off the marking on the ruler which aligned with the other end of the object.
if your question is explain how to use a ruler to measure to the nearest inch the answer would be...you have to see what inch is the object your measuring to closest to
Shafts & the members of trusses....
It depends on what object you are trying to measure. Displacement is appropriate for a medium sized, non-soluble object, of any shape. It would be pretty useless if you wanted to measure the volume of a concert hall or a needle! And it would not work for a sugar cube either. A micrometre would be appropriate for small objects with simple geometry, such as a needle or possibly a sugar cube. But is would be no use for a concert hall nor an irregular object. A ruler would be appropriate for large objects with a simple geometry such as a concert hall. But it would be no use for a needle, nor for an irregular object.
tea in a cup
To measure a foot length you could use a ruler, a yard stick, a tape measure, or any object that you knew was precisely one foot long on a side or edge.
When the object is larger than the ruler.
a ruler
ruler
You don't measure with length. You measure the length of an object with a ruler. You would use inches or metres as your units.
if your question is explain how to use a ruler to measure to the nearest inch the answer would be...you have to see what inch is the object your measuring to closest to
I'll say a ruler . . . you can do that job with only one of them.
Depends on what information you do have. But I would suggest you measure it using a ruler, tape measure or similar.
Shafts & the members of trusses....
by using a photometer
That would be a ruler, yardstick, or meterstick, depending on the system of measure you are using.
A metric ruler measures in inches and centimeters.
I would measure it with a ruler.