Transcript Chapter-01-intro

My Motivational Speech
• Focus on learning, not on grades. Learning brings
success, and life-long learning brings life-long
success.
• If I offered to hire you for one month (30 days
straight!) and offered to pay you $1,000,000 or 1
penny on the first day, but double your wages each
day, which would you accept?
• If you take the penny, you make over 5 million dollars
on the 30th day (over 10 million for the month)
• It’s how you grow that’s important, not how much you
start with!
Chapter 01
Measurements
Units
• For us to communicate “how much” something is, we
must use units.
• What if I were to offer a job to you that pays an
annual salary of 60,000 per year? Would you accept
the job?
• Three of the fundamental units used in the SI system
(SI is the most common system of units used in
science)
– unit of mass, kilogram (kg)
– unit of distance, meter (m)
– unit of time, second (s)
Unit Prefixes
prefix
meaning
power of 10
micro
one-millionth
10-6
1/1,000,000
milli
one-thousandth
10-3
1/1000
centi
one-hundredth
10-2
1/100
kilo
one thousand
103
1000
mega
one million
106
1,000,000
giga
one billion
109
1,000,000,000
tera
one trillion
1012
1,000,000,000,000
Scientific Notation
There is an easier way to express numbers so that we
don’t have to count all those digits and commas.
9850 kg = 9.85 x 103 kg = 9.85 x 106 g
299,792, 458 m/s = 2.99792458 x 108 m/s
384,403 km = 3.84403 x 105 km = 3.84403 x 108 m
The mass of the earth is 5.97 x 1024 kg. Do you really
want to write that number without using scientific
notation?
Poll
The width of a DNA molecule is about
0.0000000002 m. In scientific notation, this is
1. 2 x 10-8 m
2. 2 x 108 m
3. 2 x 10-10 m
4. 2 x 1010 m
5. None of the above.
Chapter 1
Measurement
Matter & Interactions
PHY 221 – Dr. Aaron Titus
Poll
Earth’s equatorial radius is 6378 km. What is
this number written in scientific notation?
1. 6.378 x 101 m
2. 6.378 x 10-3 m
3. 6.378 x 102 m
4. 6.378 x 103 m
5. None of the above
Chapter 1
Measurement
Matter & Interactions
PHY 221 – Dr. Aaron Titus
Unit Conversion
• Write your conversion factor as a ratio equal
to 1.
• Multiply the quantity by 1 (the conversion
factor) so that units cancel as needed.
• Multiply by 1 as many times as needed.
Poll
A football field is 100 yd long. What is its length
in meters?
1. 100 m
2. 109 m
3. 9 m
4. 82 m
5. 91 m
Chapter 1
Measurement
Matter & Interactions
PHY 221 – Dr. Aaron Titus
Poll
My office has a volume of 1000 ft3. What is its
volume in m3?
1. 394 ft3
2. 305 m3
3. 0.3 m3
4. 28 m3
5. None of the above.
Chapter 1
Measurement
Matter & Interactions
PHY 221 – Dr. Aaron Titus
Poll
Suppose that you burn 280 calories of energy while
working out for 20 minutes on an elliptical machine in
the gym. How many joules of energy did you burn?
1. 1170 J
2. 67 J
3. 280 J
4. 5600 J
5. None of the above
Chapter 1
Measurement
Matter & Interactions
PHY 221 – Dr. Aaron Titus
Poll
By measuring a person’s density, one can calculate his
% body fat. If a person has a density of 1.05 g/cm3,
what is his density in kg/m3?
1. 1.05 x 103 kg/m3
2. 1.05 x 106 kg/m3
3. 1.05 x 102 kg/m3
4. 1.05 x 104 kg/m3
5. 1.05 x 109 kg/m3
Chapter 1
Measurement
Matter & Interactions
PHY 221 – Dr. Aaron Titus
Proportionality
• Sometimes we want to know
how one variable depends on
another variable.
• For example, for a circle
so doubling the radius
increases the circumference
by a factor of 2.
• When one variable is directly
proportional to another
variable, we write
Poll
The volume of a cylinder is V = πR2h. If you
double the radius of the cylinder, how much
more volume will it have?
1. It’ll have the same volume.
2. 2 times more volume.
3. 4 times more volume
4. 8 times more volume
5. Half as much volume.
Chapter 1
Measurement
Matter & Interactions
PHY 221 – Dr. Aaron Titus