LESSON 2: Measurements (copy)

MEASUREMENT

• a collection of quantitative or numerical data that describes a property of an object or event

UNIT OF MEASUREMENT

• the most convenient system unit is the international system of units (SI)

UNCERTAINTY IN MEASUREMENT

• the difference between the value measured during a measurement (actual value) and the upper and lower limit for an expected deviation from this value

SYSTEMATIC ERROR

• an uncertainty that comes from a flaw in the equipment used or the design of an experiment. Also called as determinate error

RANDOM ERROR

• the uncertainty (experimental error) that arises from a scaler reading is considered as indeterminate error

PRECISION

• how close a set of repeated measurements are to each other

ACCURACY

• how close a measured value is to the true or accepted value

SIGNIFICANT FIGURES

• are digits in any measurement that are known with certainty, plus one uncertain digit

1.ALL NONZEROS ARE SIGNIFICANT
2.ZEROS BETWEEN NONZERO DIGITS ARE SIGNIFICANT
3.ZERO TO THE LFT OF THE FIRST NONZERO DIGITS ARE NOT SIGNIFICANT
4.IF THE NUMBER IS LESS THAN 1, THEN ONLY THE ZERO AT THE END OF THE NUMBER AND THE ZEROS BETWEEN NONZERO DIGITS ARE SIGNIFICANT
5.IF THE NUMBER IS GREATER THAN 1, THEN ALL THE ZERO WRITTEN TO THE RIGHT OF THE DECIMAL POINT ARE SIGNIFICANT
6.FOR NUMBERS WITH RAILING ZEROS BUT WITHOUT A DECIMAL POINT, THE ZERO, MAY OR MAY NOT BE SIGNIFICANT. TO CORRECT THIS, EXPRESS THE NUMBER IN A SCIENTIFIC NOTATION
7.ZEROS USED A PLACE HOLDERS IN A LARGE NUMBER WITHOUT A DECIMAL POINT ARE NOT SIGNIFICANT

• rules for significant figures

SCIENTIFIC NOTATION

• as a process of simplifying a very large number or a very small number. this is written in the form of N x 10^n

ROUNDING OFF

• is the process of removing insignificant digits from a caculated numbers

DIMENSIONAL ANALYSIS

• is a process in which a conversion factor written in a form of ratio is used to change the units given in the data to the units desired.

1.WRITE THE UNKNOWN QUANTITY THAT IS SOUGHT, INCLUDING THE UNITS
2.WRITE ALL THE KNOWN CONVERSION FACTORS NEEDED
3.BEGIN WITH WHAT IS KNOWN AND MULTIPLY IT BY THE IDENTIFIED CONVERSION FACTORS, CANCELLING SIMILAR UNITS TO GET THE UNKOWN UNIT

• the following steps for solving dimensional analysis problems

DENSITY

• describe show tightly mater is packed within a given volume

• the ratio o the mass of an object of the volume it occupies

MASS

• the quantity of matter in an object. It is determined by weighing the object, using a balance. The SI units for mass are kilogram and gram

VOLUME

• the amount of space occupied by a substance. For liquids, the volume can be determined using a graduated cylinder

1.RECTAGULAR SOLID
2.CUBIC SOLID
3.CYLINDRICAL SOLID
4.SPHERICAL SOID

• regularly shaped solids (don’t have to memorize the formula)

WATER DISPLACEMENT METHOD

• is a system of measurements used to determine the volume of an object that does ot have a regular shape.

TEMPERATURE

• tells how hot or cold an object is. It is commonly measured using either Celsius or Fahrenheit.