Transcript Scientific Notation - Menifee County Schools

Basics in Mathmatics
Why is math important?
 Read the article “Math Mistakes in History: The
Mars Climate Orbiter”
http://threesixty360.wordpress.com/2007/11/14/math-mistakes-in-history-the-mars-climate-orbiter
 Explain what went wrong with the Mars Climate
Orbiter.
/
On 9/23/On 9/23/99, $125,000,000 Mars Climate Orbiter entered
Mars’ atmosphere 100 km lower than planned and was destroyed by
heat.
99, $125,000,000 Mars Climate Orbiter entered Mars’ atmosphere
100 km lower than planned and was destroyed by heat.
1 lb = 4.45 N
“This is going to be the
cautionary tale that will be
embedded into introduction to
the metric system in elementary
school, high school, and college
science courses till the end of
time.”
What is scientific Notation?
 Scientific notation is a way of expressing really big
numbers or really small numbers.
 It is most often used in “scientific” calculations where
the analysis must be very precise.
Why use scientific notation?
 For very large and very small numbers, these numbers
can be converted into scientific notation to express
them in a more concise form.
 Numbers expressed in scientific notation can be used
in a computation with far greater ease.
 Mass of Proton:
 .00000000000000000000000167 grams
 Number of electrons passing by a point in a circuit:
 6250000000000000000 electrons per second
Scientific notation consists of two
parts:
 A number between 1 and 10
 A power of 10
N x 10x
Are the following in scientific notation?
Changing standard form to
scientific notation.
To change standard form to scientific
notation…
 Place the decimal point so that there is one non-zero
digit to the left of the decimal point.
 Count the number of decimal places the decimal point
has “moved” from the original number. This will be
the exponent on the 10.
 If the original number was less than 1, then the
exponent is negative. If the original number was
greater than 1, then the exponent is positive.
Example 1
 Given: 289,800,000
 Use: 2.898 (moved 8 places)
 Answer: 2.898 x 108
Example 2
 Given: 0.000567
 Use: 5.67 (moved 4 places)
 Answer: 5.67 x 10-4
Practice
 Use the link below to practice converting standard
form to scientific notation.
 Converting to Scientific Notation
Changing scientific notation
to standard form.
To change scientific notation to standard
form…
 Simply move the decimal point to the right for positive
exponent 10.
 Move the decimal point to the left for negative
exponent 10.
(Use zeros to fill in places.)
Example 3
 Given: 5.093 x 106
 Answer: 5,093,000 (moved 6 places to the right)
Example 4
 Given: 1.976 x 10-4
 Answer: 0.0001976 (moved 4 places to the left)
Practice
 Use the link below to practice converting scientific
notation to standard form.
 Converting to Standard Form
Even More Practice
 Below is a list of links to games and activities all having
to do with scientific notation.
 http://www.aaamath.com/dec71i-dec2sci.html
 http://janus.astro.umd.edu/cgi-bin/astro/scinote.pl
 http://www.sciencejoywagon.com/physicszone/lesson/
00genral/dectosci.htm
Now take the quiz to test your
scientific notation skills!
 Click on the link below to take the quiz and then use
the answer key for the correct answers.
 Quiz
 Answers
Metric Prefixes
Metric Prefixes
I can rearrange equations to solve
equations for specified variables.
 What is the equation for solving for speed?
 Can you rearrange the equation to find distance?
 Can you rearrange the equation to find time?
Ohms law
 defines the relationship between voltage, current and resistance.
 These basic electrical units apply to direct current, or alternating
current.
 Ohm’s Law is the foundation of electronics and electricity.
 This formula is used extensively by electricians.
 Without a thorough understanding of “Ohm’s Law” an electrician
can not design or troubleshoot even the simplest of electronic or
electrical circuits.
 Ohm established in the late 1820’s that if a voltage was applied to a
resistance then “current would flow and then power would be
consumed”.
Ohm's law magic triangle
Voltage = E or V
Current = I
Resistance = R
Ohm’s Law
If you know E and I, and wish to determine R, just eliminate R
from the picture and see what's left:
If you know E and R, and wish to determine I, eliminate I and see
what's left:
if you know I and R, and wish to determine E, eliminate E and see
what's left:
To understand electronics we must review basic
electricity.
What is Electricity?
 Everything is made of atoms
 There are 118 elements, an atom is a single part of an
element
 Atom consists of electrons, protons, and neutrons
 Electrons (- charge) are attracted to protons (+ charge),
this holds the atom together
 Some materials have strong attraction and refuse to
loss electrons, these are called insulators (air, glass,
rubber, most plastics)
 Some materials have weak attractions and allow
electrons to be lost, these are called conductors
(copper, silver, gold, aluminum)
 Electrons can be made to move from one atom to
another, this is called a current of electricity.
 Surplus of electrons is called a
negative charge (-). A shortage
of electrons is called a positive
charge (+).
 A battery provides a surplus of
electrons by chemical reaction.
 By connecting a conductor from
the positive terminal to negative
terminal electrons will flow.
Voltage
 A battery positive terminal (+) and a negative terminal (-). The
difference in charge between each terminal is the potential energy
the battery can provide. This is labeled in units of volts.
Water Analogy
Current
 Uniform flow of electrons thru a circuit is called current.
WILL USE CONVENTIONAL FLOW NOTATION ON
ALL SCHEMATICS
Resistance
 All materials have a resistance that is dependent on cross-
sectional area, material type and temperature.
 A resistor dissipates power in the form of heat
Create a Table to organize the
variables and specific
characteristics of each.
The force
or
pressure
behind
electricity
variable
Unit
milliamp or just mA
Conversions of units
•As a milliampere (milliamp or just mA) is 1/1000th of an ampere, we
can convert mA to Amps by just dividing by 1000. Another way is to take
the current in mA and move the decimal to the left three places to
accomplish the division by 1000. Here's the scoop:
275 mA / 1000 = 0.275 Amps
•Note that the decimal in 275 is to the right of the 5, and it's written as
275.0 (with a 0 added to show where the decimal is). Moving the
decimal to the left three places gets up to .275 Amps, but we usually
hang a 0 in front of the decimal.
•To convert Amps to milliAmps, just multiply by 1000 or move the
decimal to the right three places. Just the opposite of what we did here
to convert the other way.
Power
Definition
Variable
Equation
unit
Depends
on
Electrical Power
 Power is the rate of using or supplying energy:
 Power = Energy / Time
 Power is measured in watts (W)
Energy is measured in joules (J)
Time is measured in seconds (s)
Electrical Power
 Electronics is mostly concerned with small quantities
of power, so the power is often measured in milliwatts
(mW), 1mW = 0.001W.
 For example an LED uses about 40mW and a bleeper
uses about 100mW, even a lamp such as a torch bulb
only uses about 1W.
 The typical power used in mains electrical circuits is
much larger, so this power may be measured in
kilowatts (kW), 1kW = 1000W. For example a typical
mains lamp uses 60W and a kettle uses about 3kW.
Electrical Power
Besides this basic equation for power:
P = I*V
remember we also have Ohm’s Law:
V = I*R .
Challenge: Based upon the two
equations, how is power related to
resistance?
Power
Definition
Power is the rate of using or
supplying energy
Variable
P
Equation
Power = Energy
time
unit
Power is measured in watts (W)
Energy is measured in joules (J)
Time is measured in seconds (s)
Depends
on
Variable
Unit
ELECTRICAL CIRCUITS
S.MORRIS 2006
More free powerpoints at www.worldofteaching.com
circuit diagram
Scientists usually draw electric circuits using symbols;
cell
lamp
switch
wires
Simple Circuits Series circuit
 All in a row
 1 path for electricity
 1 light goes out and the
circuit is broken
 Parallel circuit
 Many paths for electricity
 1 light goes out and the
others stay on
1
2
PARALLEL CIRCUIT
 Place two bulbs in parallel. What do you notice
about the brightness of the bulbs?
 Add a third light bulb in the circuit. What do you
notice about the brightness of the bulbs?
 Remove the middle bulb from the circuit. What
happened?