Home assignment 7th Science 3/23 - 3/27 Notes

This assignment is a review of measurement used in the science setting. In most cases, science measurements are done using the metric system. Today, you will practice making measurements of length, mass, and liquid volume.

Length is measured with a ruler, meter stick, or tape measure. Units of length are centimeters (cm). Centimeters are made up of smaller units called millimeters (mm). There are 10 mm in a centimeter. A larger unit is the meter (m). A meter is 100 cm long.

Mass is a measure of the amount of matter in an object. Mass is constant in all circumstances. In contrast, weight varies with the changing force of gravity. Mass is measured in grams (g). Smaller amounts of mass are measured in milligrams (mg) and larger amounts are measured in kilograms (kg). We use a triple beam balance to measure the amount of mass an object has. To find the mass of an object.

Triple Beam Balance

Instructions on use

● The triple beam balance is used to measure masses very precisely; the reading error is 0.05 gram. ● With the pan empty, move the three sliders on the three beams to their leftmost positions, so that the balance reads zero. If the indicator on the far right is not aligned with 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 notched position immediately 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 notched position immediately 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 boldface numbers on this beam are grams and the tick marks between the boldface numbers indicate tenths of grams. ● To find the mass of the object on the pan, simply 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.

If you add up all the beams on the above balance, the mass of the object is 373.3 g.

Liquid volume is the space a given liquid takes up or occupies. We commonly measure the volume of liquid in a beaker or graduated cylinder. The unit used is milliliter (mL). A larger unit is the liter (L). For comparison purposes, a 16.9 ounce bottle of water is 500 mL. When reading the amount of liquid in a container you get at eye level with the water and read the bottom of the curve of the liquid, This is called the meniscus.