Many of the numerical values you will be dealing with in
Physics are very large or very small numbers. Written in this form,
the values of the quantities take up a lot of space and can be very
confusing to read and can be awkward to use in calculations. To
make things easier, we will always write them in scientific
notation by expressing decimal places as powers of 10. M x 10 n
where M is a number between 1 and 10 and n is an integer. To write
numbers in scientific notation, move the decimal point until only
one non-zero digit remains to the left. Then count the number of
places you moved the decimal point and use that number as the
exponent of 10. Examples: 3,1200,000 = 3.12 x 10 6 (If you move the
decimal to the left to make the number smaller your exponent is
positive) 0.00000312 = 3.12 x 10 -6 (if you move the decimal to the
right to make the number bigger your exponent is negative. Fun
Practice at
http://www.aaamath.com/dec71i-dec2sci.htmlhttp://www.aaamath.com/dec71i-dec2sci.html
Slide 3
Input the number in scientific notation is put into your
calculator correctly. Read the directions for your particular
calculator. For basic scientific calculators: Punch the number (the
digit number) into your calculator. Push the EE or EXP button. Do
NOT use the x (times) button! Enter the exponent number. Use the
+/- button to change its sign. Voila! Treat this number normally in
all subsequent calculations. To check yourself, multiply 6.0 x 10 5
times 4.0 x 10 3 on your calculator. Your answer should be 2.4 x 10
9.
Slide 4
Slope is equal to the change in the y axis divided by the
change in the x axis. The symbol means a change in so y means y 2 -
y 1 or y final y initial
Slide 5
Physics is concerned with the description and understanding of
nature, and measurement is one of its most important tools.
Measurements are expressed with a number and a unit (a standard of
measurement) If you were asked how long the room was in terms of
your shoe size, each class member would give different answers and
it could be confusing. The metric system is based on a system of
prefixes corresponding to the powers of 10. Instead of switching
names, like when we go from inches to feet, in metrics, we just
change the prefix. Another great reason to use the metric system is
that because the prefixes are based on the powers of ten, to change
prefixes, all we have to do is move the decimal place. You will be
introduced to many units in physics!
Slide 6
Metrics Little GuysBig Guys prefix symbol value
Slide 7
Derived Units
Slide 8
Used when converting between units. The value is equivalent,
but the unit has changed. You can memorize the metric conversion
factors (ex. 1 km = 1,000 m) or an easier solution is to become
familiar with the value of each metric prefix and then converting
will be a breeze!
Slide 9
Steps: 1: Write your starting measurement as a fraction 2.
Determine a conversion factor (s) 3. Write the conversion factor as
a fraction with the unit that you started with in the denominator
(so the units cancel out when you multiply). 4. Evaluate. Do the
original units cancel so you are left with ONLY the desired units?
Multiply both numbers and units. Example) 80 mi = ___ km? 1) 80 mi
1 2) 1 mi = 1.609 km 3) 4) = 128.72 km
Slide 10
15 mi/h = ______ m/s 1) 2) Conversion Factors: 1 mi = 1609 m
3600 s = 1 hr 3) 4) = = 6.70 m/s =
Slide 11
1) 2)Conversion Factors: 1 x 10 -6 s = 1s 1 x 10 6 s = 1 Ms 3)
4)
Slide 12
Practice 1) Earths escape velocity is about 11.2 km/s. How fast
is this in mi/h? (1 mi = 1.609 km) Practice 2) 7 km =
__________m
Slide 13
Practice 1) 25,059.0 mi/hr Practice 2) 7 x 10 9 s Conversion
Factors 1 km = 1000 m 1m = 1 x 10 -6 m Follow this link to a great
tutorial with practice and instant feedback Dimensional Analysis
Tutorial Dimensional Analysis Tutorial ***Remember your conversion
factors should equal the same amount! They are just in different
standards of measurement!*****
Slide 14
Be careful when converting squared and cubic units! Calculate
the volume of a box with length = 10 cm, height = 12 cm and width =
15 cm. What would its volume be in cubic inches? Note that the
cubic centimeters cancel only because the conversion factor is
cubed.
Slide 15
This is a good method for finding the resultant of two vectors
which make a right angle to each other. For instance, if you walked
11 km North and then walked 11 km east, how far are you from your
starting position?
Slide 16
Trig Functions: SOH CAH TOA
Slide 17
Assume you were in a boat, crossing a river that runs from West
to East. If you were moving 12 m/s, 65 N of East, how fast is the
river current? To answer this, diagram the problem and look for
triangles!!! Make a coordinate system (the black lines) Direction
of Water current Boat velocity 12 m/s Current speed? You are given
the hypothesis and the angle. You are looking for the adjacent
side! How can you find it using one of the trig functions?
Slide 18
The river current is moving at 5.07 m/s, East. For more help
with this go to http://www.physicsclassroom.com/Class/vectors/
http://www.physicsclassroom.com/Class/vectors/
Slide 19
ax 2 + bx + c = 0 You will, on occasion, have problems in class
that will require you to use this method.
Slide 20
Can you rearrange the following equations? solve for v f
Slide 21
t = d/v and d = vt a = 2d/t 2 and v f = v i + at
Slide 22
Diagram the problem (helps to visualize) List the given
information What are you solving for/What is the unknown? What
concepts are involved? What equation(s) will you need to use? Show
all steps Solve and do not forget a unit! This is the guess
method!