Prelab material
Include hand written prelab questions torn from the lab manual
Due at the beginning of the lab period. No exceptions.
Writing Style
Typed in a dark or black ink some accent color is ok
Use complete sentences, in paragraph form
Paper should
Astronomical Data:
Earth
5.98x1024 kg
6.38x106 m
0m
Mass
Radius
Distance from Earth
Conversion Factors:
1 atm = 14.7 psi = 1.01105 Pa
1 in = 2.54 cm
1 ft = 0.3048 m
1 mi = 5280 ft = 1609 m
1 day = 24 hr
1 hr = 60 min
1 min = 60 s
Common Densities:
water:
Beyond Energy
If we can identify every well-defined force
that acts on an object, in theory, we only need
integrals and Newtons 2nd law (as defined in
chapter 5) to solve for the motion of the
object. In the last chapter, we used the
concept of energy con
Other types of energy
We have talked about kinetic energy and
gravitational potential energy. There are
many other forms of energy. What else
have we not talked about?
1.
2.
3.
4.
Electrical potential energy
Chemical energy (electrical potential energy)
H
Uniform Circular Motion
Say that an object is traveling with a constant
(uniform) speed along a circular path. The
object is accelerating at a constant magnitude by
constantly changing direction.
This is what we call uniform circular motion.
The force cau
Force and distance
Lets consider the definition of the net force.
dv x
Fx ,net ( x) max m
dt
dv x
dx
Fx ,net ( x)v x Fx ,net ( x) mvx
dt
dt
dv x d 1 2
mvx
( 2 mvx )
dt dt
1
2
Fx ,net ( x)dx d ( 2 mvx )
1
Work
If we integrate both sides of this equation
w
Galileos Observation (1632)
Imagine any particle projected along the
horizontal plane without friction; then we know
that this particle will move along this same plane
with a motion which is uniform and perpetual
But if the plane is limited and elevated
Common sense notions of force
We can define a force as any push or
pull. We normally think that a force
acts on an object because of some
agent causing the force. Since force is
a vector, it has a magnitude and
direction. Forces can be either contact
forc
Quick Math Review: Trigonometry
We will soon need to make extensive use
of the study of triangles.
ho
sin
h
ha
cos
h
ho
tan
ha
h
ho
ha
SOH CAH TOA
1
Inverse trig functions
We can also use trigonometry to
determine the angles forming a triangle.
ho
s
Problem Solving Tactics I: Drawing
Whenever possible, draw a picture.
Physics is about observing the world and
creating a model. Drawing pictures helps
you take the words of a problem and
envision what is happening.
The pictures need not be works of art,
What is Physics?
Believe it or not, this is one of the
hardest questions we will tackle!
An easier question then, might be what
does a physicist do?
Observes something
Builds a model of what happens
Tests the model to gain insight on the world
Physicis
Physics 221
General Physics I, Fall 2012
Lecturer: Matthew Hilt [email protected]
We begin our study of Physics, including the following topics:
Motion in one-dimension
Motion in a circle
Motion in many dimensions
Forces
Energy
Momentum
Rotational moti
Some preliminary notions
1. System of interest: an ideal
gas in a container
2. Walls of container may or may
not conduct heat
3. One of the walls may be
moveable: it is a piston that
exerts a force
Thermodynamic variables:
Pressure P
Volume V
Temperature
Zeroth Law of Thermodynamics
If we place two objects in contact
and leave them for a long time,
they reach thermal equilibrium.
If we then measure the
temperature of each of these
objects separately, we must get
the same reading.
Thermometers actually rea
What is heat?
Heat is the energy transfer into a system as a
result of a temperature difference between
the system and any other object. The energy
is from motion of the system that does not
move the center of mass, including internal
motion and bond ener
Temperature
Some common sense notions:
There exists such a property as temperature that tells
us whether an object is hot or cold.
If you mix hot and cold you get warm.
Many physical properties depend upon temperature:
volume, pressure, "phase" (solid,
Superposition of
Waves
Superposition: if several
effects occur simultaneously,
the result is the sum of the
individual effects
1. If two waves y1(x,t) and y2(x,t)
overlap, then the resultant wave is
the algebraic sum of the two:
y(x,t) = y1(x,t) + y2(x,t)
Longitudinal Waves
In a longitudinal wave, the
medium vibrates parallel to
direction of energy transfer.
The wave consists of backward
and forward movement of
compressions and rarefactions
(stretching) of the medium.
Examples of longitudinal waves
include
Fluids Defined
What constitutes a fluid?
Substance that is free to flow
Conforms to the shape of its container
No shearing stress allowed
No long range order
The term fluid refers to both
liquids and gases. Everything that
we will talk about today app
Making Waves
Can we have oscillations in both temporal
and spatial coordinates?
What would they look like?
1
Wave Motion
Waves transport energy; waves do not
transmit matter. For a mechanical
wave to exist, we need a disturbance,
a medium that can be dist
Simple Harmonic Motion
AKA Acoustics 001
Any system that oscillates about an
equilibrium is governed by the rules of
harmonic motion, all you need is a
restoring force.
Earlier, we talked a little bit about the
spring-mass system. Similar physics
describe
Our starting assumptions
We have made 2 explicit assumptions about our
study of motion:
1. The motion of the object is translational
Vertical, horizontal, along a parabola, or any other shape.
There just arent any twists or rotations.
2. The object is a p
Torque from a force
Say we apply a force F, some distance r away
from the center of mass. Only the component
of force that is tangent to the center of mass
will contribute to the rotation creating a
torque. The magnitude of the torque is given
as:
r F
Equilibrium
When Newton quantified (turned into math)
his observations of force and motion he
arrived at the following conclusion:
F
a
m
or F ma
If I want to have zero change in motion, is
it sufficient to say that only the forces
must sum to zero?
1
Equ
Gravity
In our treatment of the gravitational
force, we have limited ourselves to the
form Fgrav = mg. Is this a constant or
is there more to the story?
Consider a space shuttle in low-Earth
orbit. It orbits in a circle, so if our
force rule were correct,
Atoms and isotopes
When creating an atom, the type of atom is
set by the number of protons. Hydrogen
really means, one proton; helium means
two protons, etc. The number of neutrons in
a nucleus is not fixed. Natural Hydrogen has
0, 1 or 2 neutrons; stable
Fundamental Forces
There are four fundamental forces, strong,
electromagnetic, weak and gravitational. The
strong force is incredibly short range and
responsible for bonding in the nucleus. The
electromagnetic force forms ordinary matter.
The weak force i
Bonding Potential
Bonding in a molecule is the result
of electrical forces between
atoms. A stable molecule must
have an inter-atom potential
energy with a minimum value
which does not place the atoms
infinitely far away. There are
two competing forces in
Classical Radiation
Two observations were known about radiation
from a thermal source by the end of the 19th
century, Stefans Law and Wiens Law. In
Stefans law, the power was observed to
increase as the temperature of an object to the
fourth power.
P eAT