The presented text is prepared on the basis of numerous … · The presented text is prepared on...
Transcript of The presented text is prepared on the basis of numerous … · The presented text is prepared on...
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The presented text is prepared on the basis of numerous resources which are recommended for student self studies as well:
1. D.Halliday, R.Resnick, K.S.Krane, Physics, vol.1,2, J.Wiley & Sons, Inc., New York 1992. 2. P.A.Tipler, Physics for Scientists and Engineers, W.H.Freeman & Co, 4th ed. 1999 3. H.D.Young, Physics, Addison-Wesley Publ.Co., 8th ed. 1992. 4. H.D.Young, R.A. Freedman, University Physics with Modern Physics, Addison-Wesley Publ.Co 12 ed.2007 5. E. Hecht, Physics: Calculus, Brooks/Cole, 2nd ed. 2000. 6. D.C.Giancoli, Physics, Principles with Applications, 6th ed. Pearson education Inc, 6th ed. 2005. 7. M.Mansfield, C.O’Sullivan, Understanding Physics, J.Wiley & Sons Ltd, 1998. 8. R.Resnick, D.Halliday Fizyka, 14th ed, PWN 1999. 9. D.Halliday, R.Resnick, J.Walker, Fizyka, t. 1-5, PWN 2003. 10. A.K. Wróblewski, J.A. Zakrzewski, Wstęp do fizyki, PWN 1976. 11. B.Jaworski, A.Dietłaf, L.Miłkowska, Kurs fizyki, PWN 1984. 12. C.Kittel, W.D. Knight, M.A.Ruderman, Mechanika, PWN 1973. 13. E.M. Purcell, Berkeley Physics Course, Elektryczność i Magnetyzm. 14. A.K.Wróblewski, Historia Fizyki, PWN 2007.
Internet resources: http://en.wikipedia.org http://hyperphysics.phy-astr.gsu.edu/hbase/hph.html http://physicsweb.org/resources/- simulations http://www.pintarmedia.com/-virtual lab http://www.whfreeman.com/tipler/content/instructor/index.htm http://info.fuw.edu.pl/~akw/historia.html http://ptf.fuw.edu.pl/fizyka.html- physics links http://ocw.mit.edu/OcwWeb/Physics/8-01Physics-IFall1999/VideoLectures/index.htm http://www.animations.physics.unsw.edu.au http://www.howstuffworks.com/ http://www.educypedia.be/electronics/javaelectricity.htm http://www.alcyone.com/max/physics/laws/
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Lecture 1 VECTORS
Notes:
Lecture 1- 1
„ For we do not t hi nk t hat we k now a t hi ng un t i l we are acquai n t ed wi t h i t s pri mary condi t i ons or f i rst pri n ci pl es, an d have carri ed ou r ana l ysi s asf a r as i t s si mpl est el emen t s.
Aristotle, Physics, written 350 B.C.E
Observations
Analysis
Model
Application
Experimental verification
quantities measures
standardsunits
Scientific methodLanguage of physics
„ "To measure i s t o k now.„" If y ou can not measure i t , y ou can not i mprove i t .„
Lord Kelvin
experiments
„ "Mat hemat i cs i s t he on l y good met aphysi cs."„
" I hav e no sat i sfact i on i n f ormu l as un l essI f eel t hei r nu meri cal magn i t ude."
Lord Kelvin
Maths
Scientific Method
Key terms: Scientific method, feedback, measures, units, standards
Scientific Method is a procedure involving the observation of phenomena, the formulation of a hypothesis, experimentation to evaluate the hypothesis, and a conclusion that validates or modifies the hypothesis. The final stage involves applications.
Learn more:
http://en.wikipedia.org/wiki/Scientific_method
Concepts: Mediocrity principle The principle that there is nothing particularly interesting about our place in space or time, or about ourselves. This principle probably first made its real appearance in the scientific community when Shapley discovered that the globular clusters center around the center of the Galaxy, not around the solar system. The principle can be considered a stronger form of the uniformity principle; instead of no place being significantly different than any other, the mediocrity principle indicates that, indeed, where you are is not any more special than any other. Source: http://www.alcyone.com/max/physics/laws/ Copyright © 2009 Erik Max Francis
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Problem Solving General Strategy
Lecture 1- 2 Vectors & scalars
Vector’ features: - additional directional quality• independent on the system of coordinates:
value, direction.• obeys vectors’ addition laws:
parallelogram construction, commutative law,(rotation does not obey commutative law)
Scalar’ features: - quantity•independent on the system of coordinates.•obeys algebraic rules.
Vector forms of physics laws do not depend on the coordinates system
BFV
;;
iET ;;
Tensors
scalar quantities are tensors of rank 0; Vector quantities are tensors of rank I (1 dim array)
Tensor of rank II (3x3 – 9 components)
Anisotropy: tension,moment of inertia,electric susceptibility,
Maths:multi-dimensional array relative to a choice of basis of the particular space on which it is definedPhys:tensorial quantities vary from point to point (generalised directional properties)
Tensors’ rank: number of array indices required to describe such a quantity
Key terms: Vector, scalar, tensor, rank, isotropy, anisotropy
IDENTIFY the relevant concepts: First, decide which physics ideas are relevant to the problem. Although this step doesn’t involve any calcuIations, it's sometimes the most challenging part of solving the problem. Don't skip over this step, though; choosing the wrong approach at the beginning can make the problem more difficult than it has to be, or even lead you to an incorrect answer. At this stage you must also identify the target variable of the problem-that is, is the quantity whose value you're trying to find. Sometimes the goal will be to find a mathematical expression rather than a numerical value. Sometimes, too, the problem will have more than one target variable. The target variable is the goal of the problem-solving process; don't lose sight of this goal as you work through the solution. SET UP the problem: Based on the concepts you selected in the Identify step, choose the equations that you'll use to solve the problem and decide how you'll use them. If appropriate, draw a sketch of the situation described in the problem. EXECUTE the solution: In this step, you "do the math." Before you launch into a flurry of calculations, make a list of all known and unknown quantities, and note which are the target variable or variables. Then solve the equations for the unknowns. EVALUATE your answer: The goal of physics problem solving isn't just to get a number or a formula; it's to achieve better understanding. That means you must examine your answer to see what it's telling you. Be sure to ask yourself, "Does this answer make sense?" If your target variable was the radius of the earth and your answer is 6.38 centimeters (or if your answer is a negative number!), something went wrong in your problem-solving process. Go back and check your work, and revise your solution as necessary. Source: H.D.Young, R.A.Freedman, University Physics, Pearson, Addison-Wesley, 12th ed. 2007
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Notes:
Lecture 1- 3
ABBA
)( CBACBA
BkAkBAk
)(
B
A
B
C
cos2222
ABBAC
)( BABAC
Vectors
b
b A
BC
B
A
B C
commutative law
resultant vector
vector addition
associative law
vector subtraction
CBA
Key terms: Vector algebra, associative law, commutative law, parallelogram method, tail-to-head method, vector sum (resultant)
Scalar quantity is a number and it obeys the usual rules of arithmetic. It changes when its magnitude changes. Vector quantity has direction and sense as well as magnitude and follows vector algebra rules, in particular the rules of vector addition. The change of any of the vector’s features (direction, sense, magnitude) results in a change of vector quantity. Commutative = it is independent of the order of addition The addition of rotation is non-commutative. Rotations have well-defined magnitudes and directions but they are not, in general, vector quantities.
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Notes:
Lecture 1- 4
w
A
z
wA
zA
A
xA
Components of vectors
)ˆ,(cosˆˆ xAAxxAA xx
unit vector - versor
)ˆ,(cos xAAAx
A
xxA
defines direction in space
x
r
a
r
a
raa ˆ
raa ˆ
1ˆ r
antiparallel
Key terms: Unit vector, versor, vector component, parallel vectors, antiparallel vectors, negative of a vector
Unit vector describes direction in space. A unit vector has a magnitude of one, with no units.
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Notes:
Lecture 1- 5
yx
z
A
yA
xA
zA
Vectors in a Cartesian coordinates
i
kj
zyx AAAA
kAjAiAA zyxˆˆˆ
],,[ zyx AAAA
222zyx AAAA
kA
jA
iA
ˆ,
ˆ,
ˆ,
AA
AA
AA
z
y
x
cos
cos
cos
Cartesian notation
Key terms: System of coordinates, orthogonal system, Cartesian system,
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Notes:
Lecture 1- 6
],,[ zyx AAAA
],,[ zyx BBBB
kBAjBAiBA zzyyxxˆ)(ˆ)(ˆ)(
AnC
Vectors’ operations
kAjAiAA zyxˆˆˆ
kBjBiBB zyxˆˆˆ
kCjCiCC zyxˆˆˆ
zzzyyyxxx BACBACBAC ;;
],,[ zyx CCCC
BAC
Vector products
AnAnC
knAjnAinAAnC zyxˆ)(ˆ)(ˆ)(
Key terms: Cartesian notation, Component method for adding vectors
Learn more:
http://en.wikipedia.org/wiki/Euclidean_vector
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Notes:
Lecture 1- 7
),(cos BABABA
B
A
cosA
ABBA
ABBA
0
ABBABA
//
],,[ zyx AAAA
],,[ zyx BBBB zzyyxx BABABABA
1ˆˆ ii
0ˆˆ ji
Scalar product
dot product -> numberBA
commutative law
C
1ˆˆ kk 1ˆˆ jj 1ˆˆˆ 2 iii
0ˆˆ kj 0ˆˆ ik
lFW
work
Key terms: Dot product, square of the unit vector, vector coordinates
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Notes:
Lecture 1- 8
],,[ zyx AAAA
],,[ zyx BBBB CBA
),(sin BABABA
B
A
C
ABBA
ABBA
//0
ABBABA
kBABAjBABAiBABABA xyyxzxxzyzzyˆ)(ˆ)(ˆ)(
zyx
zyx
BBB
AAAkji
BA
ˆˆˆ
Vector productcross product -> vector
in the „right-handed system”
0ˆˆ ii
kji ˆˆˆ
0ˆˆ kk0ˆˆ jjikj ˆˆˆ jik ˆˆˆ jki ˆˆˆ © W.H.Freeman & Co
Key terms: Right hand screw rule,
Learn more:
http://en.wikipedia.org/wiki/Right-hand_rule
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Notes:
Lecture 1- 9
kji ˆˆˆ ikj ˆˆˆ jik ˆˆˆ
0ˆˆ ii0ˆˆ jj0ˆˆ kk
Cartesian (orthogonal) system
kji ˆˆˆ ikj ˆˆˆ jik ˆˆˆ
iy
x
z
kj
ikji ˆˆˆˆ
Right-handed
iy
x
z
k
j
Left-handed
Key terms: right-handed system, left-handed coordinate system
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Notes:
Lecture 1- 10
yx
z
i
kj
r
yr
xr
zr
),,( zyxP
Position in a Cartesian system
zyx rrrr
krjrirr zyxˆˆˆ
],,[ zyx rrrr
222zyx rrrr
kr
jr
ir
ˆ,
ˆ,
ˆ,
rrrrrr
z
y
x
cos
cos
cos
position vector
Key terms: orthogonal system, position vector, vector module, vector coordinates
Coordinate system: A system for specifying points using coordinates measured in some specified way. The simplest coordinate system consists of coordinate axes oriented perpendicularly to each other, known as Cartesian coordinates.
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Notes:
Lecture 1- 11
),,( zrP
r
z
z
x
y
Cylindrical coordinate system
- radiusr -azimuthal anglez -elevation
zzryrx
sincos
zzyxrxyarctg
22
conversion
Key terms: coordinate conversion
Learn more:
http://en.wikipedia.org/wiki/Cylindrical_coordinate_system
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Notes:
Lecture 1- 12
),,( rP
r
x
y
z
Spherical coordinate system
-radiusr -polar angle -elevation angle
cossinsincossin
rzryrx
rz
xyarctg
zyxr
arccos
222
conversion
Key terms: global positioning system GPS
Learn more:
http://en.wikipedia.org/wiki/Spherical_coordinates
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Notes:
Lecture 1- 13
),( rP
y
x
Polar coordinate system, natural systems
r
Polar coordinate system
-radiusr -polar angle
o90
sincos
ryrx
xyarctg
yxr
22
conversion
)(r polar equation
Circle: centre , radius),( or a222 )cos(2 arrrr oo
)cos()( kar polar rose
0A
S Ss - path coordinate
Natural system
Key terms: reference axis
Learn more: :
Polar equation of a curve http://en.wikipedia.org/wiki/Polar_coordinate_system#Polar_equation_of_a_curve
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Lecture 2 DESCRIPTION OF MOTION Notes:
Lecture 2- 1 Examining the rate of change
)()( xfxxf
x
x xx
xxfxxf
xf
)()(
)(xf
differential quotient
xxx
fxxfxf )()(
)(xf
xxf
tanaverage change
instantenous rate of change ?
variable changes
function responds
Key terms: secant line, tangent line
Average change does not mean algebraic average (mean value.)
Learn more: http://ocw.mit.edu/ans7870/resources/Strang/strangtext.htm
Calculus, Gilbert Strang: e-book
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Notes:
Lecture 2- 2Instantenous rate of changederivative concept
x
)(xf
x
dxxx dfdxxfxf )()(dxx 0
instantenous rate of change
)(')()(lim
0xf
dxdf
xxfxxf
x
derivative)(' xfdxdf
slope of the tangent line
x
)(' xf
x
)(xf
Key terms: rise over the run,
People Standing on the shoulders of giants Infinitesimal calculus
Gottfried Wilhelm von Leibniz http://en.wikipedia.org/wiki/Leibniz
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Notes:
Lecture 2- 3 Calculation of derivatives (1)
)(')()(lim
0xf
dxdf
xxfxxf
x
0)( dxdfCxf
dxdfCxCf
dxd
))((
1)( nn nxdxdfxxf x
dxdfxxf 2)( 2
33)( dxdfxxf
aaadxd xx ln
xx eedxd
xx
dxd 1ln
axx
dxd
a ln1log
xxdxd cossin
xxdxd sincos
xx
dxd
2cos1tan
xx
dxd
2sin1cot
properties:
‘power rule’
from def.
Key terms: limiting case, power rule,
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Notes:
Lecture 2- 4 Calculation of derivatives (2)
dxdg
dxdfxgxf
dxd
))()(( 323)( 2 xdxdfxxxf
fdxdgg
dxdfxgxf
dxd
))()(( xxxxdxdfxxxf cossin2sin)( 22
2'')
)()((
gfggf
xgxf
dxd
dxdu
dudf
dxdfxuf )]'(([
xxxx
dxdf
xxxf 2sin
cos2sin2sin2)(
)cos(2)sin()( 22 xxdxdfxxf
compound function
Key terms: chain rule
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Notes:
Lecture 2- 5 Derivatives (3)
),( yxf
2
2
)())('(dx
fddxdf
dxdxf
dxd
66333)( 3
3
2
223
dxfdx
dxfdx
dxdfxxxf
Multivariable functions
higher order derivatives
3
3
2
2
dxfd
dxfd
dxd
xy yf
xf
partial derivatives
2
2
2
2
yf
xf
xyf
yf
xyxf
xf
y
22
)(xfy dxxfdy )(')(' xfdxdy
differential
dfdgxfxg
)()(
differentiation
- 20 -
Notes:
Lecture 2- 6 Kinematics
Spacetime
Frame of reference
Ideal frame of reference
Isotropic Euclid space
Material point
Rigid body
Concept of motion
Learn more: Spacetime is any mathematical model that combines space and time into a single continuum. Spacetime is usually interpreted with space being three-dimensional and time playing the role of a fourth dimension that is of a different sort than the spatial dimensions. According to certain Euclidean space perceptions, the universe has three dimensions of space and one dimension of time. more at:
http://en.wikipedia.org/wiki/Spacetime
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Notes:
Lecture 2- 7
yx
z
i
kj
r
yr
xr
zr
),,( zyxP
Position in a cartesian system
krjrirr zyxˆˆˆ
],,,[ trrrr zyx
time: 4th dimension
Euclid spaceclassical mechanics
],,[ zyx rrrr
How many dimensions are neededto describe the universe???
Speculative theories such as string theory predict 10 or even 26 dimensions!
Relativistic contexts:time cannot be separated from space(time depends on an object's velocity)
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Notes:
Lecture 2- 8 Equations of motion
Cartesian system
)();();()(
],,[
tztytxtr
zyxr
Cylindrical system)();();(
),,(tzttr
zrP
Spherical system)();();(
),,(tttr
rP
equation for path coordinates vs time
0A
S )(tS - path coordinate
Describing motion: equation of motion
Positional vector vs timeCoordinates vs timeTrajectory equation
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Notes:
Lecture 2- 9
)()()(
tzztyytxx
),( yxfz
x
y
zTrajectory
Key terms: trajectory of motion
Motion Capture Data MOCAP Capturing marker-trajectories In order to biomechanically analyze the motion of a person or in order to map real world performances onto virtual characters, captured marker-trajectories, e.g. 3D trajectories of optical beacons attached to the body, have to be transformed into the motion parameters of a kinematic skeleton model.
Learn more: http://cat.wiki.softimage.com/index.php/Mapping_Motion_from_Mocap_Point_Clouds
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Notes:
Lecture 2- 10
y
x1r
2r
r
s
1r
2r
r
1v
2vO
trv
t
0lim
dtrdv
Displacement, velocity
rrr 12
Average velocitytrvav
instantaneous velocity
Key terms: speed, velocity vector, global change, instantaneous change
Average velocity is not the mean value of the velocity.
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Notes:
Lecture 2- 11
dtrdv
zyxzyx vvvvkvjviv ˆˆˆ
.
.
.
zdtdzv
ydtdyv
xdtdxv
z
y
x
222zyx vvvv
vv
kv
vv
jv
vviv
z
y
x
)ˆ,cos(
)ˆ,cos(
)ˆ,cos(
Instantaneous velocity
dtdr
kdt
drj
dtdri zyx ˆˆˆ
dtdzk
dtdyj
dtdxi ˆˆˆ
r
x
y
zv
xvyv
zv
ij
k
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Notes:
Lecture 2- 12
1r
2r
a
1v
2v
O
vtv
dtvd
tva
t
0
lim
dtrdv
2
2
dtrd
dtvda
2
2
2
2
2
2
dtzda
dtyda
dtxda
z
y
x
222zyx aaaa
2
2
2
2
2
2
2
2ˆˆˆ
dtzdk
dtydj
dtxdi
dtrda
zyx aaaa
zyx akajaia ˆˆˆ
zayaxa
zvyvxv
zyx
zyx
,,
,,
Acceleration
tvvaav
12
jerk (jolt ): 3
3
dtrd
dtad
Key terms: Newton notation, Leibnitz notation
Any change of any of the velocity characteristics (e.g. magnitude, direction, sense) produces acceleration
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Notes:
Lecture 2- 13
Curvilinear motion
01
P 1
P
0
nV
s
skav
Average curvature
velocity versorradius versorn
local curvature
radius of curvature
kdds 1
dsd
sk
s
lim0
dsd
Key terms: curvature, convex, concave, centre of curvature, radius of curvature,
- 28 -
Notes:
Lecture 2- 14
1
dtdV
dtdV
dtVda ˆˆ)ˆ(
2sinˆ2ˆ
2
2sin
ˆˆ lim0
2
d
versor increment
ˆˆ
dtd
ˆ n
a
VP
P 1 r s
O
n n
Planar curvilinear motion
dtdn
dtd ˆˆ
dtdnV
dtdVa ˆˆ
A
dd 1ˆ
VV
2
2sin
ˆ
Key terms: versor increment
Time derivative of the versor (versor increment) defines another versor which perpendicular to the given one.
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Notes:
Lecture 2- 15
Vdtds
nt aanV
dtdVa
ˆˆ
2
22
2
dtdVa
V
22nt aaa
V
s
O
an
Tangent and normal acceleration
dtds
dsdnV
dtdVa ˆˆ
dtdnV
dtdVa ˆˆ
dtdVat
nVan ˆ2
at
an
1
dsd
radius of curvature
tangent normal
- 30 -
Notes:
Lecture 2- 16
rs
rs
22
rs
V
rdtdr
dtds
dtd
dtdVat
rVan
2
4222 raaa nt
fT
const 22
)(t
2
2
dtd
y
xr
Circular motion
s
dtdr
2
2
dtdr
dtdtdd
r
r
r2
angular velocity
angular acceleration
Key terms: angular path,
- 31 -
Notes:
Lecture 2- 17
0
rV
dtVda
dtd
V
ryx
z
tarrdtd
vdtrd
navdtrd
rvan
)()()( baccabcba
rat
Circular motion – acceleration (s)
rran
)()(
rdtd
dtrdr
dtd
r 2
© W.H. Freeman & Co
Key terms: angular velocity, right hand rule, normal acceleration, centripetal acceleration
In a uniform circular motion the direction of velocity vector changes. That directional change is due to the centripetal acceleration.
- 32 -
Notes:
Lecture 2- 18
nt aavra
rvan 2
rat
V
r yx
z
anat
rr
van2
2
rat
Circular motion – vectors
Key terms: tangent (linear) acceleration, radial (normal) acceleration
- 33 -
Notes:
Lecture 2- 19
y
xr
)(t )cos(cos 0 trrx)sin(sin 0 trry
)sin( 0 trdtdxvx
)cos( 0 trdtdyv y
xtrdt
dva xx
20
2 )cos(
ytrdt
dva y
y2
02 )sin(
nyx araaa 222
Uniform circular motion in polar coordinates
Uniform circular motion can be described as result of overlapping of two linear , simple harmonic oscillations along perpendicular directions, shifted in phase by:
2