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