how scientists use measurements to collect data

1. Section 3:
Measurement
Standard Measurement System
• Minimizes confusion among scientists all over the world
• Allows scientists to compare data and communicate with
each other about the results
• Metric System — developed in France in the 1790s
• a.k.a. International System of Units (SI)
Chapter 1 Introduction to Physical Science

2. A Standard Measurement System
Using SI as the standard system of measurement allows
scientists to compare data and communicate with each other
about their results. SI units are based on multiples of 10.
Chapter 1 Introduction to Physical Science

3. Metric Length
The basic unit of length in SI is the meter (m).
•Very small objects can be down to the nanometer (nm)
•Very large objects in kilometers (km)
•Common tool: metric ruler
Chapter 1 Introduction to Physical Science

4. Length
Chapter 1 Introduction to Physical Science

5. Weight
a measure of the force of gravity on an object
SI unit for weight is the Newton (N)
weight is based on the pull of gravity on your mass
weight depends on location
Chapter 1 Introduction to Physical Science

6. Mass
•a measure of the amount of matter and object contains
•The SI unit of mass is the kilogram (kg).
• mass does NOT change with location
•Common tool: triple beam balance
Chapter 1 Introduction to Physical Science

7. Mass
Chapter 1 Introduction to Physical Science

8. Volume
the volume of space an object takes up
SI unit of volume is the cubic meter (m3
).
Chapter 1 Introduction to Physical Science

9. Volume
Meniscus – the curved upper surface of a liquid in a column
of liquid
Chapter 1 Introduction to Physical Science

10. Volume
Volume of solids = LxWxH
Chapter 1 Introduction to Physical Science

11. Density
density is mass per unit volume
Chapter 1 Introduction to Physical Science

12. Density
Sink or Float?
Object sink if their density is more than that of water
Objects float if their density is less than that of water
Density of water :
Chapter 1 Introduction to Physical Science

13. Calculating Density
Suppose that a metal object has a mass of 57 g and a
volume of 21 cm3
. Calculate its density.
Read and Understand
What information are you given?
Mass of metal object = 57 g
Volume of metal object = 21 cm3
Chapter 1 Introduction to Physical Science

14. Calculating Density
Suppose that a metal object has a mass of 57 g and a
volume of 21 cm3
. Calculate its density.
Plan and Solve
What quantity are you trying to calculate?
The density of the metal object = __
What formula contains the given quantities and the unknown
quantity?
Density = Mass/Volume
Perform the calculation.
Density = Mass/Volume = 57 g/21 cm3
= 2.7 g/cm3
Chapter 1 Introduction to Physical Science

15. Calculating Density
Suppose that a metal object has a mass of 57 g and a
volume of 21 cm3
. Calculate its density.
Look Back and Check
Does your answer make sense?
The answer tells you that the metal object has a density of
2.7 g/cm3
. The answer makes sense because it is the same
as the density of a known metal–aluminum.
Chapter 1 Introduction to Physical Science

16. Calculating Density
Practice Problem
What is the density of a wood block with a mass of 57 g
and a volume of 125 cm3
?
0.46 g/cm3
Chapter 1 Introduction to Physical Science

17. Calculating Density
Practice Problem
What is the density of a liquid with a mass of 45 g and a
volume of 48 mL?
0.94 g/mL
Chapter 1 Introduction to Physical Science

18. Density
Because density is actually
made up of two other
measurements–mass and
volume–an object’s density is
expressed as a combination
of two units. The density of a
substance stays the same no
matter how large or small a
sample of the substance is.
Chapter 1 Introduction to Physical Science

19. Time
The second (s) is the SI unit of time.
common tool is the stopwatch
Chapter 1 Introduction to Physical Science

20. Temperature
Common tool – thermometer
Celsius scale – temperature scale on
which water freezes at 0° and boils at
100°
Chapter 1 Introduction to Physical Science

21. Temperature
Kelvin scale— temperature scale on
which zero is the temperature at which
no more energy can be removed from
matter
•Kelvin (K) is the SI unit of temperature.
• 0° Kelvin is called absolute zero
•Absolute zero is equal to -273°C
Chapter 1 Introduction to Physical Science