PHYS

ICAL S

CIENCE C

H 2

Standard –

Exact quantity that people agree to use for comparison

Purpose - When all measurements are made with same standard, measurements can be compared

Measurement system –

English

Metric- multiples of 10

International System of Units - 1960

CHAPTER 2

-Units of measurement and standards-Length -Mass-Time -Temperature-amount of a substance (atoms/molecules)-Electrical current-luminosity

-3 types of graphs

LENGTH

-The distance between two points

SI Base Unit = meterSI is based in powers of ten:-deci- means 1/10-centi- means 1/100

100 cm = 10 dm = 1 m

USING MATH

How many centimeters are in 1.98 meters?

Problem-Solving Steps:

1. What is known? 1 m = 100 cm

2. When converting from larger units (m) to smaller (cm) you multiply

1.98 m x (100 cm/1 m) = 198 cm

VOLUME

-The amount of space occupied by an object

-If length, width, and height are expressed in centimeters, then volume (length x width x height) is expressed in: cm3 “cubic centimeters”

-No tool can measure volume, so combine 2 SI Units (refer to p 38)….

-Volume units are derived units;

- 1 Liter = 1 cubic decimeter (dm3)

PRACTICE PROBLEM W/ VOLUME

ANSWER

538 / 1000 = 0.538 L

MASS

A measurement of matter in an object

SI unit is kilogram (kg).

For objects of small mass, grams (g) or milligrams (mg) are used

Convert from g to kg, etc.

DENSITY

-Like volume, density is a derived unit

-Mass per unit volume, or mass/volume (g/mL)

-Each material has its own unique density

TEMPERATURE

The amount of thermal energy (heat) in a substance.

**For now, think of temperature as “how hot or cold something is”

-Temperature is measured on the Celsius (c) scale-Water at freezing = 0 degrees C; water at boiling

= 100 degrees C-SI Unit is Kelvin (K) = NO DEGREE SIGN!!; find

Kelvin by adding 273 to the Celsius temperature

HOMEWORK

p. 56 # 1-10, 16-21

DUE THURSDAY!

2.3: GRAPHS

Line Graphs: ‘

-used to show trends or how data changes over time

- What information is shown here?

GRAPHS

Bar Graphs:

- Useful for comparing information collected by counting

- Height corresponds to a number of (y)

- This bar graph shows…?

GRAPHS

IMPORTANCE OF GRAPHS

- A visual display of informationor data- Who uses graphs?

- Businesses- Sports, sport agents, coaches- Economics- Politics- Engineering- Science and research- ???Anyone else???

HOMEWORK

p. 56 # 13, 14, 22, 23

Slope: y = mx + b

Two points, subtract y-y and x-x:

m = (y1-y2)/(x1-x2)