Precision Measuring1.1.3A

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– 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)

Steel Rule

Micrometer

Tools for Precision Measuring

Digital Caliper

Dial Caliper

Tools for Precision Measuring

The dial caliper is a precision measuring instrument.

The caliper’s blade graduations arein inches and tenths (.1) of an inch.

Reading a Dial Caliper

inch

Each inch is broken into ten, for .1 of an inch.

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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.

Reading a Dial Caliper

One full revolution of the pointer on the dial equalsone hundred thousandths (.100).

Blade

Inside Measuring Faces

Outside Measuring Faces

Dial

Fine Adjustment Screw

Dial Clamp Screw

Clamp Screw

Dial Caliper Parts

Step 1 Read inches from the blade

1 in. – 6 in.

2

Reading a Dial Caliper

Step 2 Read tenths of an inch from the blade

Reading a Dial Caliper

1 in. – 6 in. .0 in. -.9 in.

2 3

Step 3 Read thousandths of an inch from the dial

Reading a Dial Caliper

1 in. – 6 in. .0 in.- .9 in. .001 in.- .099 in.

2 3 2 8

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 Rule Tape Measure

Dial Caliper Meter 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