MEASUREMENT TOOLS

INTRODUCTION When scientists make observations, it is not sufficient to say something is “big” or “heavy”. Instead scientists use instruments to measure just how big or heavy an object is.

INTRODUCTION By measuring, scientists can express their observations more precisely and better communicate the information about what they observe.

INTRODUCTION If you wanted to measure the length and width of the classroom, which SI unit would you use? How would you measure the amount of matter in your textbook? How would you measure the amount of water that a drinking glass would hold?

INTRODUCTION In order to answer these questions you must have a grasp of the system you are to use to make the measurements, but more than that you must know what tools to use and how to use them to measure effectively.

WHAT TOOLS ARE USED Length: meter meter sticks and metric rulers Mass: gram triple beam balance Liquid Volume: liter graduated cylinder for liquids Temperature: degrees Celsius Celsius thermometer

SPECIAL NOTE Regular Solids are measured by taking length x width x height width height length

SPECIAL NOTE Regular solid volume is measured in cubic units. Use meter sticks or metric rulers Example: cm3 is the abbreviation for cubic centimeters

MEASURING LENGTH When measuring with a ruler be sure to measure from the beginning mark on the ruler, not the end of the ruler. Be as accurate and precise as possible. Know your marks.

RULERS

START AT THE MARK NOT THE END OF THE RULER

MEASURING MASS Make sure the balance is balanced before starting. Always start with the largest rider and work to the smallest rider. Add all three beams together to get the total mass. REMEMBER - Mass and weight are not the same thing.

READING THE BEAMS 100 gram rider 10 gram beam 10 gram rider 1 and tenths gram beam 1 and tenths gram rider

The Triple Beam Balance 1 gram rider pointer pan 10 gram rider 100 gram rider zero mark 10 gram beam (back) 100 gram beam (middle) tare adjustment base 1 gram beam (front)

MEASURING LIQUIDS Make sure the cylinder is on a flat surface. Read the bottom of the meniscus not the sides. Lean over so you are looking in a straight line at the meniscus.

MEASURING LIQUIDS Not every graduated cylinder uses the same scale. Know the units you are measuring in before you start. Look at the scale on the cylinder.

GRADUATED CYLINDERS Notice that each has a different scale.

OBJECTIVES Learn the tools for measurement of each of the units in the SI. Learn the abbreviations for the prefixes and base units of the SI.

IN QUESTION Could you use your bathroom scale to weigh an elephant? Why or why not?

VOCABULARY Accuracy is the correctness of the measurement. ex: when playing darts, you are more accurate when you are closer to the bull’s eye.

VOCABULARY Precision is how well you or an instrument takes a measurement. ex: a scale is precise if gives the same weight for the same object every time you weigh it .

VOCABULARY Meniscus – curved line of a liquid in a graduated cylinder.

NOTES Length: - meter sticks and metric rulers Mass: - triple beam balance Volume of liquids: - graduated cylinder Special Note: Volume of regular solids: length x width x height

NOTES Ruler Use the beginning mark, not the end of the ruler. Be accurate and precise. Know your marks.

NOTES Triple Beam Balance Balance scale before starting. Start with the largest rider, work to the smallest rider. Add all beams together to get total mass.

NOTES Graduated Cylinder Read bottom of the meniscus not the sides. Place cylinder on a flat surface. Look in a straight line at the meniscus. Know the scale of the cylinder.

OUT QUESTION Measure the width of your table with your hand. How wide is it? Did everyone get the same answer? Why or why not?