measurement. stating a measurement in every measurement there is a number followed by a unit from...
TRANSCRIPT
Measurement
Measurement
In this chapter we will explore the following concepts:
1. Measurement of a physical parameter
2. Units, systems of units
3. Basic units in mechanics
4. Changing units
Stating a Measurement
In every measurement there is
a
¨ Number
followed by a
¨ Unit from measuring device
Standards of Measurement
When we measure, we use a measuring tool to compare some dimension of an object to a standard.
SOME TOOLS FOR MEASUREMENT
Basic & Derived Quantities
Basic Quantity Must be defined in terms of a standard (meter, kilogram, second).
Derived Quantity Defined in terms of combinations of basic quantities
Unit of speed = meter/second = m/s
International System of Units:In this system the units for the base quantities are:
Parameter Unit Name Symbol
Length meter m
Mass kilogram kg
Time second sec or s
Unit of Length: the Meter
A meter is a unit of length, currently defined as the distance light travels within 1/299782458th of a second.
Time Unit –second (s)The time needed for a cesium-133 atom to perform 9,192,631,770 complete oscillations
Volume Unit – the Liter (L)
1 gallon = 4 quarts
1 liter (L) = 1.06 quart
1 quart = 946 mL
1 L = 10 deciliters (dL)
= 100 centilliters (cL)
= 1000 milliliters (mL)
Volume is the amount of space occupied by a substance.
S.I unit of volume is liter (L).
The milliliter (ml) is commonly used for measuring smaller volumes of fluids.
Mass
The mass of an object is a measure of the
quantity of material it contains.
In the SI system, the mass unit is the
kilogram (kg).
In the metric system, the mass unit is the
gram (g).
Compare to US weight units:
1 kg = 2.20 lbs
1 lb = 454 grams
Temperature Scales
The degree of hotness or coldness is called temperature.
The S.I unit of temperature is kelvin
Other Scales:1. Celsius (C) scale
2. Fahrenheit (F) scale
1 C = 1.8 F
Other Systems of Units
CGS centimeter-gram-second
FPSfoot-pound-second
From the previous slide, state the tool (s) you would use to measureA. temperature ____________________B. volume ____________________
____________________C. time ____________________D. weight ____________________
Learning Check
From the previous slide, state the tool (s) you would use to measure
A. Temperature thermometerB. Volume measuring cup, graduated
cylinderC. Time watch, clocksD. Weight spring balance
Unit conversions
We will work exclusively in SI (MKS) units!
Unit Conversion
What are some S.I units that are used to measure each of the following?
A. length
B. volume
C. weight
D. temperature
Learning Check
Some possible answers are
A. length inch, foot, yard, mile
B. volume cup, teaspoon, gallon, pint,
quart
C. weight ounce, pound (lb), ton
D. temperature °F
Units in the Metric System
length meter m
volume liter L
mass gram g
temperature Celsius °C
Learning Check
Identify the measurement in metric units. A. John’s height is1) 1.5 yards 2) 6 feet 3) 2 meters
B. The volume of Pepsi in a big bottle is1) 1 liters 2) 1 quart 3) 2 pints
C. The mass of a lemon is1) 12 ounces 2) 145 grams 3) 0.6
pounds
Solution
A. John’s height is3) 2 meters
B. The volume of Pepsi in a big bottle is
1) 1 liter
C. The mass of a lemon is2) 145 grams
Changing Units
Units of Volume:• The SI unit of volume is the cubic meter (m)3.
• A more convenient unit of volume for everyday use is the liter, a non-SI unit.
• A liter (L) is the volume of a cube that is 10 centimeters (10 cm) along each edge (10 cm 10 cm 10 cm = 1000 cm3 = 1 L).
Units and QuantitiesUnits of Temperature
Scientists commonly use two equivalent units of temperature, the degree Celsius and the kelvin.
Units and Quantities
The joule (J) is the SI unit of energy. One calorie (cal) is the quantity of heat that raises the
temperature of 1 g of pure water by 1°C.
Section Quiz.1. Which of the following is not a base SI unit?
grammetersecondmole
Section Quiz.
3. A temperature of 30 degrees Celsius is equivalent to
303 K. 300 K. 243 K. 247 K.
THE END