Physics: Unit 1: Prelims & Motion
6 most common metric multipliers (bonus: 2 more)
(tetra) 1. giga 2. mega 3. kilo 4. milli 5. micro 6. nano (pico)
what caused the Mars Climate Orbiter mission to fail?
- NASA worked in lbs and ESA worked in Newtons, so the ESA engine saw 10 lbs & interpreted it as 10 N. the ESA engine used too much force for the actual weight --> explosion - they had 2 incompatible metrics & forgot to double check
why do we use Kelvin?
0 degrees Kelvin = 0 kinetic energy (rather than a large, negative number -- there are no negatives)
1/10
0.1
1/9
0.11...
1/8
0.125
1/6
0.166...
1/5
0.2
1/4
0.25
1/3
0.33...
1/2
0.5
the SI assigns ______ for each _________
1 standard unit physical quantity
How do you measure the position of an object?
1. Choose Origin 2. Find the distance from the Origin 3. Write it in the x=#m format
Process of Science
1. Come up with an Idea 2. Perform an Experiment 3. Does the evidence support the Idea? a) Yes --> THEORY --> Additional Experiments b) No --> Idea is wrong! --> Try Again
What physical quantities are associated with motion?
1. Position 2. Speed 3. Velocity 4. Time
every country has adopted the SI except for
1. US 2. Liberia 3. Burma (actually Myanmar)
3 controls that can cause acceleration:
1. gas pedal: increase speed 2. brake pedal: decrease speed 3. steering wheel: change direction
what are the 2 components to measurement?
1. physical quantity 2. unit of measure
why do we have so many units? (3 reasons)
1. realistically measuring big and small 2. different physical quantities 3. different cultural measurements (historical purposes)
micro- (symbol and factor)
10^-6
when did scientists create the International System of units(SI)?
1960
energy (symbol & SI unit)
E, joule(J)
why is the Earth an oblate spheroid?
Earth spun when not completely solid --> buldges
The observations made by Eratosthenes do NOT support the flat earth theory, what does this mean?
Eratosthenes had to come up with a new idea and test it!
write to power of 10: during a jump, a grasshopper pushes the ground with 16 mN of force
F = 16 x 10^-3 N
force (symbol & SI unit)
F, Newton(N)
Newton's 2nd Law of Motion
Force = mass x acceleration
giga- (symbol and factor)
G 10^9
who is the father of modern science?
Galileo Galilei
electric current (symbol & SI unit)
I (captial i), ampere(A)
mega- (symbol and factor)
M 10^6
does acceleration occur? a car moving at a constant speed in a straight-line path
NO -- uniform motion!
power (symbol & SI unit)
P, Watt(W)
tera- (symbol and factor)
T 10^12
temperature (symbol & SI unit)
T, Kelvin(K)
acronym for metric multipliers
To (tera) Get (giga) More (mega) Kind (kilo) Millions of (milli) Mice (micro) Need (nano) Peace (pico)
define unit fraction
a fraction with a numerator of 1
define Scientific Notation
a mathematical method of writing numbers using powers of ten
scientific notation
a mathematical method of writing numbers using powers of ten
what does the SI provide to adjust the size of the SI Units?
a set of decimal-base multipliers (or prefixes)
define unit of measure
a standard used to measure a physical quantity
acceleration equation
a=vf-vi/∆t
the law of falling bodies
all freely falling bodies, on Earth, fall with acceleration equal to 9.8 m/s downward (g≈-10m/s²)
what is a scientific theory?
an explanation of a natural phenomenon that agrees with all known evidence
what is science?
an organized way of building & organizing knowledge in a testable form with predictions & explanations (knowledge confirmed by experimentation)
define physical quantity
any characteristic of an object that can be measured
Scientific Notation Formulas
a•10^b 1≤a≤10 b=all real #'s
define acceleration
change in velocity (speed or direction)
what is the International System of Units?
consists of - base units - units of measure - a set of decimal-based multipliers with prefixes
∆
delta (change in)
Is a lightyear a measure of time or distance?
distance
negative powers of ten __________ by 10
divide by 10
why are the 6 most common metric multipliers useful?
easier to understand, multiply, and memorize most useful for objects
why did we establish an International System of Units?
every scientist will used the same metrics that are compatible so they Mars Climate Orbiter incident doesn't happen again.
write to power of 10: an Inter Core processor runs at a clock rate of 3.70 GHz
f = 3.7 x 10^9 Hz
frequency (symbol & SI unit)
f, Hertz(Hz)
"Measure what is measurable and make measurable what is not so." (Galileo Galilei) Meaning?
find a way to measure something
acceleration does not measure
how fast an object is moving or can move
why would using 1 unit of measure to measure everything in the universe be problamatic?
humans don't do well with numbers 1000+ -- we like smaller numbers
When is an object in motion?
if it changes position relative to a reference point
name the appropriate unit of measure: the length of a pencil
inches
why does the International System of Units abbreviate as SI?
it originated in France (système international d'unités)
kilo- (symbol and factor)
k 10^3
milli- (symbol and factor)
m 10^-3
write as scientific notation: m = 5,980,000,000 kg
m = 5.98 x 10^9 kg
mass (symbol & SI unit)
m, kilogram(kg)
why is acceleration squared?
m/s/s = m/s x 1/s = m/s²
SI unit for acceleration
m/s² (m/s/s)
why is it hard to get an exact measure of something?
materials provided aren't perfect
name the appropriate unit of measure: the distance between 2 cities
miles
negative power of 10
move decimal to the left number of spaces of the exponent
positive power of 10
move decimal to the right number of spaces of the exponent
positive powers of ten __________ by 10
multiply
nano- (symbol and factor)
n 10^-9
why are some SI base units capitalized?
named after scientists
an object is throw up. what is the acceleration?
negative
when the ball is momentarily at rest, what is the acceleration?
negative
making number bigger
negative power
uniform motion
object moves w a constant speed in a straight-line path
accelerated motion
object moves with a changing velocity (speed or direction)
the Earth is an
oblate spheroid
pico- (symbol and factor)
p 10^-12
'write down a measurement of the physical quantity in each situation' format
physical quantity = # unit of measure ex: x=8.1m x=distance & physical quantity m=meters & unit of measure
making number smaller
positive power
electric charge (symbol & SI unit)
q, Coulomb(C)
a car going left brakes. what direction is the acceleration?
right
a car speeds up. what direction is the acceleration?
same as velocity
a sports car passes a police car. the police car needs to catch the sports car. what type of motion is needed?
some other type of motion --> accelerated motion - NOT rest or uniform motion
What instrument measures car speed?
speedometer
What instruments measure velocity?
speedometer & compass
Clock Reading (symbol, SI unit, define)
t s a point in time
write to power of 10: there are 86.4ks in one day
t = 86.4 x 10^3 s
time (symbol & SI unit)
t, seconds(s)
the word physics comes from
the Greek word physis, which means nature
the English word science comes from
the Latin word scientia, which means knowledge
which is going faster?: CAR v=0.7x10^2m/s TRAIN v=5x10^1m/s
the car - car goes 70m/s & train does 50m/s - v=7x10^1m/s (CAR) > v=5x10^1m/s (TRAIN)
define physics
the natural science that involves studying matter & its motion & behavior through space & time & the related entities(life) of energy & force (the study of the natural world)
a car remains at the same speed. what direction is the acceleration?
there is no acceleration
a bowling ball and feather are dropped at the same time into a vacuum chamber. which falls faster?
they fall at the same rate
what is the goal of physics?
to build mathematical models to explain the relationships between quantities
why do we study physics?
to understand the world with quantitative reasoning & problem-solving skills
name the appropriate unit of measure: the weight of a car
tons
Speed (symbol, SI unit, define)
v m/s how fast
a ball falls down. what direction is velocity & acceleration?
v & a are both down
write as scientific notation: t = 0.04 x 10^-7 m/s
v = 4 x 10^-9 m/s
a ball is hit up. what direction is velocity & acceleration?
v is up, a is down
velocity equation
v=∆x/∆t
change in velocity formula
vf-vi=a(tf-ti)
Velocity (symbol, SI unit, define)
v→ m/s how fast and which way
why can we never know if a theory is true?
we only know that no evidence has yet been found to disprove the theory
at what point should we accept a scientific theory as being true?
we should never accept it as truth bc there is still unknown evidence out there
If the Earths curved, then why does it look flat when you are standing on its surface?
we're so small that a very large curve appears to be straight
Position (symbol, SI unit, define)
x m a point in space
distance (symbol & SI unit)
x, meters(m)
does acceleration occur? speedometer is moving
yes -- change in speed
does acceleration occur? car turns at unknown speed
yes -- changes direction
object moves in same path as same speed. what is the acceleration?
zero
change in position formula
∆x=xf-xi xf = position final xi = position initial
