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Precision Measuring 1.1.3A. Precision Measuring. Precision – How close together or repeatable the results are A precise measuring instrument will give nearly the same result each time that it is used. Accuracy – How close a measurement is to the accepted value
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Precision Measuring • Precision – How close together or repeatable the results are • A precise measuring instrument will give nearly the same result each time that it is used. • Accuracy – How close a measurement is to the accepted value • For example, a balance loaded with a standard 100 g weight should read 100 g. If it doesn’t, then the balance is inaccurate. Precision measuring tools are needed for accuracy
Precision Measuring Precision measuring tools are needed for accuracy http://phet.colorado.edu/en/simulation/projectile-motion Try launching a piano with an angle of 2, 80, and 85 degrees (change initial speed to 28)
Tools for Precision Measuring Steel Rule Micrometer
Tools for Precision Measuring Digital Caliper Dial Caliper
Reading a Dial Caliper The dial caliper is a precision measuring instrument. The caliper’s blade graduations are in inches and tenths (.1) of an inch. inch { Each inch is broken into ten, for .1 of an inch.
Reading a Dial Caliper The caliper’s dial graduations are in thousandths (.001) of an inch. The reference edge keeps track of larger increments; the dial is for smaller increments.
One full revolution of the pointer on the dial equals one hundred thousandths (.100).
Dial Caliper Parts Inside Measuring Faces Clamp Screw Dial Blade Fine Adjustment Screw Dial Clamp Screw Outside Measuring Faces
Reading a Dial Caliper 1 in. – 6 in. Step 1 Read inches from the blade 2
Reading a Dial Caliper Step 2 Read tenths of an inch from the blade 3 2 .0 in. -.9 in. 1 in. – 6 in.
Reading a Dial Caliper Step 3 Read thousandths of an inch from the dial 2 2 8 3 1 in. – 6 in. .0 in.- .9 in. .001 in.- .099 in.
Dial Calipers Measure • Thickness or Outside Diameter
Dial Calipers Measure • Thickness or Outside Diameter • Inside Diameter or Space Width
Dial Calipers Measure • Thickness or Outside Diameter • Inside Diameter or Space Width • Depth
Dial Calipers Measure • Thickness or Outside Diameter • Inside Diameter or Space Width • Depth • Step Distance
Discussion Questions • List measurement tools… Steel RuleTape Measure Dial CaliperMeter Stick • Explain which one of the tools listed would be best to use and why when measuring: • The hallway • Engineering Notebook • Pencil diameter • Height of your desk
Image Resources Microsoft, Inc. (2008). Clip Art. Retrieved October 10, 2008, from http://office.microsoft.com/en-us/clipart/default.aspx Wikimedia commons (2008). Retrieved October 15, 2008, from http://commons.wikimedia.org/wiki/ImageCaliper