Work and Kinetic Energy
v1
v2
Fnet
x
Object undergoes uniform acceleration from v1 to v2 in
From kinematics:
2
v2 v12 2ax
2
2
v2 v1
a
2x
Dynamics:
F ma
Fnet ma
Work:
Wnet Fnet x cos
Wnet
2
v2 v12
m
x cos 00
2x
Define
1
2
mv
2
as Kinetic Energy
Uni
Density
m
V
Units
: kg/m3
Other Units : g/cm3 , lbs/ft3
Example: Water: 1000 kg/m3 = 1.00 g/cm3
Specific Gravity (Relative Density)
S . G.
object
;
water at 4 C
water at 4 C
kg
1000 3
m
Dimensionless
Examples: Blood plasma: S.G. =
1.03
Whole blood:
Archimedes Principle
Any
body completely or partially submerged in
a fluid is buoyed up by a force equal to the
weight of the fluid displaced.
Submerged Object Includes sinking
object, object on bottom, or neutrally buoyant
object.
B = Buoyant force
A
FT
Ohms Law
I is directly proportional to V
i.e. if V is doubled, I is doubled, IF R is constant.
Resistance is caused by collisions of charge carriers with the
atoms of the medium.
V
I
R
; R is measured in ohms
volt
ohm
; Symbol :
ampere
Usually written :
CURRENT RATE OF MOVEMENT
OF CHARGE
dQ
I
dt
Ampere = Coulomb/second
Analogous to volume flow rate for fluids
Typical Currents:
100 W light bulb ~ 1A
Electric Heater ~ 10A
Electric Starter ~ 80A
Electronic Circuits ~ mA or A
CONVENTIONAL CURRENT
Direction
Electric Potential &
Electric Potential
Difference
Electric Potential Background
Mechanical Concepts
Force  Vector quantity
Gravitational Field  Vector quantity
Potential Energy  Scalar quantity (easier)
Electrical Concepts
Force (Coulombs Law)  V
Viscosity
Since there is fluid friction (viscosity), a constant force must be
applied to the upper plate to keep it moving.
The force F
is
A the area of the plates and to
the upper plate.
v
the velocity of
The force F is inversely proportional to l
Theref
Electrical Power
Energy P.E.b P.E.a
Power
t
t
dqV
dt
P = IV
Interpretation:
Rate at which potential energy of charges are
increased as they pass through the battery.
Rate at which chemical energy is decreased in the
battery.
Power  Looking at Resisto
Types of Circuits
Series
Parallel
Series Parallel Combination
More Complex
Series Circuit
Two circuit elements are in series if a
path passing through one of them
MUST pass through the other, there is
no other possible path out between
them.
Characteristi
Electric Field  Concept
A disturbance in space caused by the presence
of charge, such that another charge
experiences a force when in this disturbed
region.
Definition:
F
E
q0
Electric Field  Concept II
q0 is a
F
E
q0
small,
positive test charge.
Electric Charge
Rubber
rod rubbed with fur is negatively
charged.
Glass rod rubbed with silk is positively charged.
These
are historical designations assigned by
Ben Franklin.
Observations About Charges
Like
charges repel.
Unlike charges attract.
El
PY 205 TEST 3
NAME:_
PROFESSOR: BRUNNER
DATE: November 25, 2014
Show all work in the space provided. No credit will be given for unsupported answers.
1) An electron and a proton are separated by a distance of 1.0 m. What happens to the
magnitude of the fo
PY 205 TEST 3
NAME:_
PROFESSOR: BRUNNER
DATE: April 7, 2015
Show all work in the space provided. No credit will be given for unsupported
answers.
1) A child pulls on a wagon with a force of
If the wagon moves a total of
what is the average power delivered
Electric Charge
Rubber
rod rubbed with fur is negatively
charged.
Glass rod rubbed with silk is positively charged.
These
are historical designations assigned by
Ben Franklin.
Observations About Charges
Like
charges repel.
Unlike charges attract.
El
Electrical Power
Energy P.E.b P.E.a
Power
t
t
dqV
dt
P = IV
Interpretation:
Rate at which potential energy of charges are
increased as they pass through the battery.
Rate at which chemical energy is decreased in the
battery.
Power  Looking at Resisto
Physics 205 Final Outline
Tuesday, December 15, 2014
1:00 pm Location TBA
2 Hour Exam
The test will consist of 40 multiple choice questions. There will be a mix of short
problems and conceptual questions.
New Material
25 to 40 % of the exam
Ch 17 Electric
Vectors
Components
F
F
y
Fx
Fx F cos
Fy F sin
Here F is in the first quadrant
and both Fx and Fy are
positive.
Components (cont.)
Fx
F
F
y
Fx F cos
Fy F sin
is the reference angle the angle
between F and the nearest x axis.
Here F is in the fourth qua
Types of Circuits
Series
Parallel
Series Parallel Combination
More Complex
Series Circuit
Two circuit elements are in series if a
path passing through one of them
MUST pass through the other, there is
no other possible path out between
them.
Characteristi
Projectile Motion
Principles
In the absence of air resistance the vertical
motion of an object is unaffected by the
presence of horizontal motion.
The horizontal motion is at constant velocity.
(i.e. zero acceleration horizontally)
Equations
y directio
Power
Power is the rate of energy transfer or
the rate of doing work.
E W
P
t
t
Average
power
Where: E = energy; t = time; W =
Work
Units: 1 Joule/1second = 1 Watt (W)
1 horsepower (hp) = 746 W
Example: Average power to climb stairs
W mgh
P
t
t
Work don
Newtons First Law
(Law of Inertia)
An object at rest will remain at rest, and an object
in motion at constant speed along a straight line
(i.e., moving at constant velocity) will remain in
that motion UNLESS acted on by an unbalanced
force (or net force,
1.
MISCONCEPTUAL QUESTIONS
A truck is traveling horizontally to the right (Fig. 438). When the truck starts to slow down, the crate on
the (frictionless) truck bed starts to slide. In what direction could the net force be on the crate?
(a)
(b)
Straight do
Normal Force
Object at rest or moving along a
horizontal surface at constant velocity:
.
N
Fy =
0
NW=0
W
N=W
For an object on a horizontal surface, with only the
forces N and W acting, the normal force equals the weig
Normal Force (cont.)
Object on a hori
Fluid Dynamics
Assumptions for Ideal Fluids
Incompressible
Density of fluid remains
constant.
Non Viscous no fluid friction.
Steady Flow Velocity of fluid at EACH point
remains constant in time.
Streamline flow No turbulence.
Continuity Equation
m2
m
Force of Friction
A contact force.
The interaction of a body with its
surroundings.
Examples:
(Sliding along a surface)
(Moving through the air)
(Rolling friction)
Static Friction
Prevents an object from beginning to slide.
Friction force equals applied f
Kinematics  Study of
motion without concern
about what causes it.
Dynamics  Study of the
cause of changes in motion.
Force

Qualitative  a push or a pull.
an interaction between two bodies.

between by the common or joint action
of
Quantitative  (
Gravitational Potential Energy In a
Uniform Gravitational Field
(Near the Surface of the Earth)
Wext = mg(y2 y1) cos 00
y
2
Fex
y2 y1 = h is the change in the gravitational
U
Potential energy
t
y1
mg
Wext= mgh = Ugrav
WGrav = mg(y2 y1) cos 1800
WGrav=  m
Equations of Motion
Constant Acceleration
One Dimension
a const
dv
a
dt
Rearranging:
dv a dt
vf
Integrating Both Sides:
t f
t
dv
a
dt
v0
t
0
When: t=0,
t=tf,
v= v0
v=vf
Equations of Motion continued
Velocity Equation
v
vf
v0
a t
tf
0
v f v 0 at f 0
Rear
05 Section 1 Name
A rofessor: Brunner Exam 2 March 10, 2015
Be sure to bubble in your ID and your Name on the answer sheet.
For the problems, please show your work in the space provided. No
credit wiil be given for unsupported answers.
1) A rocket moves
PY 205 Section 1
Professor: Brunner
Name _
Exam 2
March 10, 2015
Be sure to bubble in your ID and your Name on the answer sheet.
For the problems, please show your work in the space provided. No
credit will be given for unsupported answers.
1) A rocket mo