Presentation on theme: "Measurement Using the International System (SI)"— Presentation transcript:
1 Measurement Using the International System (SI) Key question:What are the basic units of measurement in the SI system?
2 SI System The standard system used by scientists is the SI system. Scientists use SI units to measure length, volume, mass, density, and temperature.KHDBDCM : easy way to remember how to convert your units.
3 Length Basic unit of length in the SI system is meter (m). Centimeter (cm) – one-hundredthMillimeter (mm) – one thousandthKilometer (km) – kilo means 10001 meter = 100 cm1 meter = 1000 mm1000 meters = 1 km
4 Volume Volume is the amount of space an object takes up. The basic unit of volume is the liter (L).Milliliter (mL) – used to measure volumes smaller than a liter.Liters and milliliters are used to measure the volume of liquids.The SI unit used to measure the volume of solids and the liquids in shots is called cubic centimeters (cm³) or (cc)A cubic centimeter is equal to a milliliter.
5 VolumeCubic centimeters are often used in meauring the volume of liquids as well as solids.1 liter (l) = 1000 milliliters (ml) or 1000 cubic centimeters (cm³)
6 Mass Basic unit of mass in the SI system is the kilogram (kg). Mass is the amount of matter in an object.A kilogram (kg) is about 2.2 pounds.What is your mass in kilograms?Gram (g) – used to measure smaller objectsMilligrams (mg) – used to measure even smaller objects.
8 Density Density is defined as the mass per unit volume of a substance. Density = mass ÷ volumeSuppose a substance has a mass of 10 grams and a volume of 10 milliliters. If you divide the mass of 10 grams by the volume of 10 mL you obtain the density:D= 10 g ÷ 10 mL = 1 g/mL
9 TemperatureThree common scales for measuring temperature Fahrenheit, Celsius, and Kelvin.In Fahrenheit, there are 180 degrees between the boiling point and the freezing point of water. Boiling point of water = 212, freezing point of water = 32, body temperature = 98.6, room temperature = 68
10 TemperatureIn the SI system, temperature is measured on the Kelvin or Celsius scales.Water freezes at 0 degrees Celsius and boils at 100 degrees Celsius.Normal body temperature in humans is 37ºC .Comfortable room temperature is about 21ºC.
11 TemperatureFor the Kelvin scale, the boiling point of water is K, freezing point = K, body temp = K , and room temp = KO Kelvin, a.k.a. “absolute zero” is the point at which all molecular motion stops
12 Dimensional AnalysisDimensional analysis is the skill of converting one unit to another.Dimensional analysis involves determining in what units a problem is given, in which units the answer should be, and the factor to be used to make the conversion from one unit to another.To perform dimensional analysis, you must use a conversion factor.A conversion factor is a fraction always equal to 1.
13 Dimensional Analysis 1000 grams = 1 1 kilogram 1kilogram or grams = 1Which conversion factor should you use to change 2500 grams into kilograms?2500 grams x 1 kilogram1000 gramsNext, cancel out the same unitsNext step is multiply: 2500 x 1 kilogram1000Which equals 2500 kilogram= 2.5 kilograms