SCIENCE CHAPTER 1 1.3

scientists estimate that there are more than how many stars in the Milky Way galaxy?

200 billion

water boils

212 F (Fahrenheit) 100 C (Celsius) 373 K (kelvin)

the speed of light is how fast?

300,000,000 meters per second

water freezes

32 F 0 C 273 K

average room

68 F 20 C 293 K

human body

98.6 F 37 C 310 Kelvin

giga

G billion (10 9square) 1,000,000,000

what does SI stand for?

International System of Units or Systeme International d'Unites

to convert between kelvins and degrees Celsius

K-C + 273

mega

M million (10 6square) 1,000,000

one of the units used to measure temperature is the degree

celsius

electric charge

coulomb A*s C

deci

d tenth (10 -1square) 0.1

a degree Celsius is almost twice as large as a

degree fehrenheit

additional SI unitis, are called

derived units made from combinations of base units

frequency

hertz 1/s Hz

precison

is a gauge of how exact a measurement is.

conversion factor

is a ratio of equivalent measurements that is used to convert a quantity expressed in one unit to another unit.

thermometer

is an instrument that measures temperature, or how hot an object is.

accuracy

is the closeness of a measurement to the actual value of what is being measured.

energy

joule kg*m 2 square/s 2 square J

kilo

k thousand (10 3square) 1000

the base unit for mass, or the quantity of matter in an object or sample is the

kilogram (kg)

density

kilograms per cubic meter kg/m 3 square is the ration of an objects mass to it volume density=mass/volume to derive the SI unit for density, you can divide the base unit for mass by the derived unit for volume. dividing kilograms by cubic meters yields the SI unit for density, kilograms per cubic meter (kg/m 3square)

the volume of a rectangular box equals

length times its width times its height.

milli

m thousandth (10 -3square) 0.001

In SI, the base unit for length or the straight-line distance between two points is the

meter (m)

micro

millionth (10 -6square) 0.000001

amount of substance

mole mol

nano

n billionth (10 -9square) 0.0000000001

pressure

pascal kg/m*s 2 square Pa

why is scientific notation useful?

scientific notation makes very large or very small numbers easier to work with. when multiplying numbers written in scientific notation, you multiply the numbers that appear before the multiplication signs and add the exponents. when dividing numbers written in scientific notation, you divide the numbers that appear before the exponential terms and subtract the exponents.

what units do scientists use for their measurements?

scientists use a set of measuring units called SI, or the International System of Units. the abbreviation SI stands for the French name Systeme International d'Unites. SI is a revised version of the metric system, developed in france in 1791. inches, feet, and degrees Fahrenheit are not units that are used in science.

time

second s

area

square meter m 2 square

volume

the amount of space taken up by an object

how does the precision of measurements affect the precision of scientific calculations?

the precision of a calculated answer is limited by the least precise measurement used in the calculation.

mass

the quantity of matter in an object or sample. SI base unit kilogram (kg)

length

the straight line distance between two points. SI base unit meter (m)

seek time

the time it takes for a computers hard drive to read or write data

temperature

SI base unit kelvin (K)

the SI unit for temperature is the kelvin (K).

a temperature of 0 K, or 0 kelvin, refers to the lowest possible temperature that can be reached. C=5/9 (F-32.0) F=9/5(C) + 32.0

scientific notation

a way of expressing a value as the product of a number between 1 and 10 and a power of 10. example: the number 300,000,000 written in scientific notation is 3.0 x 10 (8 squared). the exponent, 8, tells you that the decimal point is really 8 places to the right of the 3. for numbers less than 1 that are written in scientific notation, the exponent is negative. the negative exponent tells you how many decimals places there are to the left of the 8.6.

electric current

ampere A

measurement consists of a number

and a unit

measurements are important in both science

and everyday life

significant figures

are all the digits that are known in measurement, plus the last digit that is estimated.

SI is built upon seven metric units known as:

base units

centi

c hundredth (10 -2square) 0.01

luminous intensity

candela cd