Video Transcript
The numbers shown on the ruler of
the figure below correspond to a number of centimeters. What is the least nonzero length in
centimeters that the ruler can measure? Is it (A) one or (B) five?
Here, we are given a figure showing
a ruler that is marked in only three locations along its length: one mark at zero
centimeters, another measuring five centimeters, and the third marking 10
centimeters. We are asked what is the least
nonzero length in centimeters that we could measure with this ruler. Let’s refresh our memories about
rulers and how we should use them.
A ruler is a straight strip of
material that has marks that are placed at various measurements along the length of
the ruler. The measurements will always start
at zero and increase to some value of length at the other end of the ruler. When measuring some length or
object, we must line the zero mark of the ruler up with the end of the length we are
measuring.
Another important thing to remember
is to get an accurate measurement of length, the ruler must be set parallel to the
length you are wanting to measure. Because the marks on a ruler
indicate the length from the zero point, we can only get an accurate measurement if
a length ends at one of these marks. If the length ends in between
marks, we can’t be sure of its correct measurement.
In order to help with this problem,
many rulers have smaller marks in between the numbered marks. These smaller marks can help
measure objects more precisely by having more lengths along the ruler to measure
with. The smallest length that can be
measured by a ruler, the distance between the smallest marks, is known as the
minimum resolution of the ruler. Looking again at the ruler we are
given in this problem, it has only three marks. Because the ruler’s minimum
resolution is the smallest distance that can be measured and is defined as the
smallest length between two marks, the minimum resolution of this ruler would be
five centimeters.
Therefore, the least nonzero length
that can be measured by this ruler is five centimeters. So option (B), five, is the correct
answer.
