Physics of human affairs test 1 Flashcards
Aristotle’s achievements
rules of formal logic
rules of writing drama
optics
taxonomy
anatomy
Aristotle’s physics
formed off observations!
- if you drop a rock, it will fall
- a rock falls faster than a feather
- INCORRECTLY CONCLUDED that things fall according to their weight
-water rolls downhill
-flames leap upward
-sky exhibits repeatable patterns (day and night phases of the Moon seasons)
- if you push a cart and let go, it will come to a stop
aristotles model of physics
linked w model of cosmology
divided everything into 5 elements
eath (solids)
water (liquid)
air (gas)
fire (heat)
aether (the sky)
Natural motion
the five elements seek their own place in the universe
-eath seeks to move downward
-water seeks its place above earth
-air seeks its place above air
-fire seeks its place above air
-aether (celestial motion) mostion of the planets stars etc.
violent motion
motion influenced by humans or animals
Galileo
- 1610 regognized the weaknesses of Aristotle’s physics
- he saw the value in aristotle’s observation-based approach
- further developed aristotle’s methods into what we now call the scientific process
galileo’s scientific process
studied motion using the following tools
- experiment or a controlled observation designed to test a specific hypothesis
-idealization or eliminating external influences. For example, minimizing friction as much as possible
-limiting the scope of inquiry to answer one question at a time
-quantitative methods. take measurements and do math
Inertia
Hypothesis (aristotle) : a moving object eventually comes to a stop, due to its natural motion
Observation (Galileo): if you minimize friction a ball rolling on a flat surface will keep rolling
Aristotle’s hypothesis was contradicted
- Hypothesis (Galileo): a moving object has inertia or a tendency to keep moving
Law of Inertia
an object in motion will stay in motion until an external force acts on it
(newton’s first law of motion)
i.e. friction
Delta symbol
means “change in”
t means
time
delta t means change in time
x means
position
delta x means
change in position
straight-line distance between start and finish
speed
a change in position over a very small time
delta x/ delta t
units of speed
meters per second m/s
kilometers per second km/h
miles per hour mph
velocity written out
60 km/h westbound
vector
a quantity (like velocity) that includes a direction
velocity
a speed and a direction
acceleration
a change in velocity over time
deta v/ delta t
units of acceleration
meters per second squared (m/s^2) feet per second squared (ft/s^2)
Galileo also created…
The laboratory!
acceleration is a vector meaning…
-it has direction
-to speed up is to accelerate forward
-to slow down is to accelerate backward
direction of motion and acceleration can be different
what is an example of centripetal acceleration
to turn a corner is to accelerate inward, toward the center of the curve
how to NOT accelerate
stay still
move in a straight line with constant speed
freefall
falling with no influence except gravity
falling without air resistance
Hypothesis of freefall (galileo)
objects in freefall accelerate downward as they fall
Galileo’s freefall experiment
falling objects are hard to study because they move too fast
solution: slow them down
instead of dropping a ball, let it roll down a gentle slope
galileo’s freefall analysis
as the slope gets steeper, the ball moves closer and closer to a state of freefall
galileo’s law of falling
if air resistance is negligible, all objects fall in the same way
general acceleration due to gravity
an object in freefall accelerates toward Earth at about 10 m/s2
Newton’s Discoveries
Developed calculus
so did leibniz but they were rivals
concepts for newtonian physics
velocity- a speed and direction
acceleration- a change in velocity. in other words, a change in speed or direction
mass- amount of matter in an object
force- push or pull
principles for newtonian physics
law of inertia: an object in motion will stay in motion unless acted on by a force
- the law of inertia was discovered by galileo and further studied by newton
- sometimes called newtons 1st law
law of falling: all objects in freefall (wiht no air resistance) fall with the same acceleration
- the law of falling was discovered by galileo and further studied by newton
principles discovered by newton
the law of motion (newtons 2nd law)
the law of force pairs (newtons 3rd law)
the law of gravity
Force!!!
an influence that can cause an acceleration
they’re external!
units of force
american : lbs
metric : Newton (N)
Newton is also a unit of weight
your weight is the force with which gravity pulls you
net force
a force is an influence that can cause acceleration
a net force is an influence that does cause acceleration
it is an imbalance of forces acting on an object
mass
mass is the amount of matter in an object
mass is like weight, except weight depends on gravity and mass does not
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