Significant_Figures_Supplement_F05

Significant_Figures_ - Department of Engineering Education Virginia Polytechnic Institute and State University Copyright J C Malzahn Kampe 2004

Info iconThis preview shows pages 1–2. Sign up to view the full content.

View Full Document Right Arrow Icon
Department of Engineering Education Fall 2005 Page 1 of 6 Virginia Polytechnic Institute and State University Copyright: J. C. Malzahn Kampe, 2004, 2005 Significant Figures Supplement EngE 1024 First, let’s look at the definitions of four basic terms that will be used in this document. significant figures – in a number, the digits beginning with and including the left-most non-zero digit and ending with the digit in the decimal place to the right that contains the first occurrence of uncertainty. Examples (digits with an “s” above are significant, those with “n” are not): n.nnssss s.ss x nn n sss.s sss ss? 0.003070 2.00 x10 4 700.0 241 120 (see page 2) place-holder zero – a zero digit that is used only to place the decimal point in the proper place and the significant figures in their proper value columns (e.g., ones place, tenths place). Place- holder zeros are not significant figures. Examples (zeros with “p” above are placeholders, those with “s” are significant figures): n.ppssss s.ss x np n sss.s sss ss? 0.003070 2.00 x10 4 700.0 241 120 (see page 2) This is a “leading zero.” It is not a significant figure, but it is not a place-holder zero either. accuracy – the closeness of a measured value to the true value for the quantity being measured. precision – in replicate testing (running the same test many times), precision is “repeatability” or the closeness of the measured values to each other – which is not the same as closeness to the true value for the quantity. In a single test, precision is how closely the measurement reading can be made, which is usually half of the smallest division that can be read on the scale of the instrument. Significant figures tell you how precisely a value is measured – they have nothing to do with accuracy. Let’s look at an example. Suppose you have a scale that measures mass in kilograms and the zero on the scale has not been set properly, hence all readings are “off” by one kilogram. Now, let’s say that you use the scale to measure your mass. You report your mass as 64.1 kg, which reflects the precision with which your scale can be read (one half of the smallest scale division). The use of three significant figures, the last of which falls in the tenths place, implies only that you are able to read the scale to
Background image of page 1

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
Image of page 2
This is the end of the preview. Sign up to access the rest of the document.

This note was uploaded on 10/02/2008 for the course ENGE 1024 taught by Professor Dcohanehi during the Fall '06 term at Virginia Tech.

Page1 / 6

Significant_Figures_ - Department of Engineering Education Virginia Polytechnic Institute and State University Copyright J C Malzahn Kampe 2004

This preview shows document pages 1 - 2. Sign up to view the full document.

View Full Document Right Arrow Icon
Ask a homework question - tutors are online