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# Measuring mass

What do we use triple beam balances for?

To measure masses very precisely. The reading error is only 0.05 gram  ( 5/100th of a gram)

With the pan empty, move the 3 sliders to their leftmost positions, so that the balance reads zero.

If the indicator on the far right doesn’t point to the fixed mark, then calibrate the balance by turning the set screw on the left under the pan.

Once the balance has been calibrated, place the object to be measured on the pan.

Move the 100 gram slider along the beam to the right until the indicator drops below the fixed mark.

The notch to the left of this point indicates the number of hundreds of grams.
Now move the 10 gram slider along the beam to the right until the indicator drops below the fixed mark.

The notch to the left of this point indicates the number of tens of grams.

The beam in front is not notched; the slider can move anywhere along the beam.

The bold numbers on this beam are one-grams.

The tick marks between the bold numbers indicate tenths  ( 1/10) of grams.
To find the mass of the object on the pan, simple add the numbers from the three beams.

As with a ruler, it is possible to read the front scale to the nearest half tick mark.

Here is how to read the beams:

## Learning Standards

Massachusetts Science and Technology/Engineering Curriculum Framework

Building on : Skills of Inquiry, Experimentation, and Design:
• Select and use appropriate tools and technology (e.g., calculators, computers, balances, scales, meter sticks, graduated cylinders) in order to extend observations.
• Keep accurate records while conducting simple investigations or experiments.
• Conduct multiple trials to test a prediction. Compare the result of an investigation or experiment with the prediction.

America’s Lab Report:  Investigations in High School Science (2005)