What is the difference between a straight edge and a ruler?

Question

What is the difference between a straight edge and a ruler?

Answer 1

A straight edge could be a book, a piece of paper, or a pencil.

Anything that's straight is usually considered a straight edge. A ruler is simply a ruler.

Usually, a straight edge is substituted for a ruler.

Answer 2

A straight edge is any object that has no curve in a plane.  The conventional ruler is a straight edge with standard linear units of measure (like cm, m, in, foot).  So the real difference is that one is marked for measuring, while the other is not.

Answer 3

A straight edge is defined by its name. An Englishman once pointed out to me that a ruler is a king or any head of State, a rule is the correct name for a graduated scale.

Answer 4

Precision. Use.

A straight edge does not need to have measuring units on it. When it does the accuracy of those units is much closer than a standard ruler because the line which they are on (the edge) is guaranteed straight.

Rulers are for general measuring in non critical applications. Their edge may not even be straight. You might even have a circular ruler to measure the distance around the edge of a curve.

So to restate it- A ruler measures distance whether it is straight or not. When a straight edge has distance units on it it only measures in a straight line.

Answer 5

the purpose of use. The straight edge is used for making a straight line , a ruler is for a measurement. although one might be able to use one for both jobs.

When one ask for a straight edge, the task is understood better, same with ruler.

Answer 6

A straight edge can be anything that is constantly uniform,(like a straight road,a table with a longer distance...)but a ruler is something used to take measurements of an object in a small distance.

Answer 7

Actually, the correct teminology is as follows:

straight edge: Can be used for drawing straight lines

ruler: used for drawing straight lines, ruling them

  but commonly used for "scale"

scale: used for measurements along a straight line.

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