Common Metric Units and Tools Used to Measure

1. Length – straight line distance between two points. meter (m) = 39 1. Length – straight line distance between two points. meter (m) = 39.4 inches

Ways to measure length: A. Ruler A ruler is the basic tool used to measure any kind of length. A ruler, or a yardstick, is just a length of wood or metal with small grooves marked in its surface at certain intervals

B. Retractable Metal Tape A retractable long length of metal tape which is used to measure large sheets of material. This model has a lock to prevent the tape from moving. For non-precise, relatively long measurements, use a tape measure.

C. Micrometer The micrometer is used to measure small diameters and thickness of thin materials. It is normally used with metal. sometimes known as a micrometer screw gauge, is a device incorporating a calibrated screw used widely for precise measurement of small distances in mechanical engineering and machining as well as most mechanical trades

D. Digital (vernier) calipers Digital (vernier) calipers are most commonly available in 150 and 200mm measuring sizes. The primary use of a digital caliper is the measurement of the thickness of an item.

You put the object between the two largest jaws, pull them snugly together around it and make your reading

Answer: reading = 36,4 mm or 3,64 cm or possibly 36,45 mm or 3,645 cm

If you want to measure the inner diameter of these contact holes, you use the small sharp jaws on the other side. You pull them apart until they press against the sides of the holes, and make your reading on the same scales as the other jaws.

In the bottom end of the caliper is a narrow tongue that sticks out as long as the distance between the jaws. You can use it to measure the depth of a hole. Put the bottom of the scale body against the edge of the hole. Pull the jaws apart until the narrow tongue presses against the bottom of the hole

2. Volume – amount of space a substance occupies A. Solid (such as a brick) – would use V = l x w x h units are often expressed as cubic meters (m3) or cubic centimeters (cm3 = cc ) Solid volume of irregular shaped objects can be measured by water displacement

Liquid - has no sides to measure so you look at the capacity in a container. Most common units are ml and liters. An important conversion is: 1 mL = 1 cm3 = 1 cc = 1 gm

Ways to measure liquids: a) Graduated Cylinder A graduated cylinder is a piece of laboratory glassware, cylindrical in shape and graduated, used to accurately measure out volumes of liquid

b) Pipettes There are many types of pipettes but most are essentially a fancier version of a medicine dropper or eye dropper. They are used in a laboratory to measure a specific volume of liquid

c) Erlenmeyer flask or volumetric cylinder An Erlenmeyer flask or volumetric cylinder is a common laboratory instrument with a wide base and thin neck. The thin neck makes it easy to swirl the contents inside. The flasks are typically made of glass and come in multiple sizes. Each size has its own graduated markings on the sides.

3. Mass – measure of the amount of matter in an object Ex: golf ball vs. ping pong ball Each have about the same volume but mass is different. Golf ball has about 18x more mass

Measuring mass: Triple balance beam Digital scales Scales use gravity, balancing its force on the astronaut's body against a calibrated spring or against the force of gravity on some calibrated weights.

Mass vs. Weight Mass is amount of matter in an object. Weight is the measure of gravity’s effect on something (force) units are Newtons (N) for metric and pound (lbs) for English system. Ex: move to a different planet and weight changes but mass stays the same weightlessness not masslessness !!

Important Temperatures Temperature – measure of the amount of molecular movement Important Temperatures Centigrade (C°) Fahrenheit (F°) Results 0° 32° Water freezes 21° 70° Room temperature 37° 98.6° Average Body Temp 100° 212° Water boils

Time – duration; common unit is seconds (s) Measuring devices: A) stopwatch B) digital timers

Mole – the amount of a substance (mol) a) a mole = 6.022 x 1023 of a substance Ex: a mole of popcorn = 6.022 x 1023 of kernels of popcorn Enough popcorn to cover the entire US at a height of 310 ft!