SAT物理常用公式
SAT II PHYSICS
Vector and Forces
torque=force length of moment arm
the sum of the clockwise moments=the sum of the counterclockwise moments
?Motion and Forces
av distance covered
average speed=
time required
displacement average velocity=time distance covered=average speed time
S=v change in velocity acceleration=
time required for change Motion with cons f i t v v v
a t t
?-== tant acceleration (starting from rest)
/2
()
av f f f v v v at v gt ===222211()222(2)
average speed
final velocity
acceleration
elapsed time
distance covered
2
f f av f i
f av S at S gt v as v gs v v a t s v v v =
========+=2
2212
2change in momentum=mass change in velocity
momentum=mass velocity
f i i f i v v at
S v t at v v as
Ft =+=+=+=??Centripetal Force
2
c v a r
=
2
22122
24Gravitational Fields
c mv F r
r v T
r a T
Gm m F r v ππ=====Work, Energy, Simple Machines
2
1kinetic energy=2
mv distance force ? =work gravitational potential energy=mgh
2
force of friction during motion
coefficient of sliding friction=
normal
work against friction=friction distance object moves
1elastic potential energy=kx 2
force distance time work power time
power ?=?=
1122
1122112212change in length=oringinal length coeff. of expansion temp. change
V V V=volume, T=absolute temperature, P=pressure
T T p V p V p V p V T T ???=???=???=??
Measurement of Heat
F V
heat required for melting=mass H heat required for vaporization=mass H heat gianed(or lost)=mass sp.ht.temp.change
+mass melted heat of fusion
????+mass vaporized heat of vaporization
?Heat and Work; Heat Transfer
heat flow=change ininternal energy+work done by system
Q=U+W
Wave Motion and Sound
Periodic Motion
For a stretched spring:
2For waves:
1 (=wavelength)the number of beats=the difference between the two frequence
Closed Pipes =4Vibrating Air Columns Open Pipe a F kx T T f v f l λλλ=-???=??
?=???=??
s =2=2a s
l l λλ?????????Geometrical Optics: Reflection and Refraction
12
For a special mirror the focal length is equal to one-half of the radius of the spherical shell /2
Law of Refraction
sin (index of refraction)sin f R n n θθ===
2112
speed of light in vacuum(or air)
speed of light in the substance
sin sin Images Formed by Lenses
111object distance image distance focal length
111size of image image distance size of object o n n n d i d o f
θθ==+=+==()bject distance
magnification m =
2focal length of the objective
telescopic magnification=
focal length of the eyepiece
intensity of source illmination distance =Physical Optics: Interference and Diffraction
x
d wavelength
d=distance between the two silts
L=distance between the barrier and the screen
x=distance between the central maximum and the first bright fringe L
λ
λ=
=Static Electricity —Electric Circuits
12
2
/ (E=electric field intensity,F=the force exerted on positive charge q)
work potential difference=charge
/ (E=electric field intensity,V=the difference of potential between the pl kq q F r E F q work V q
E V d =
===2
ates)
length in meters R=resistance in ohms A=cross-sectional area in meter //T T
T T T T
T T T
work V q L ρL R A I ρ=a constant for the material and is called resistivity; unit is ohm-meter V R R V I V I R ==???=????===
T V emf Ir
=-22;;/P VI P I R P V R
energy power time
====?Magnetism; Meters, Motors, Generators
(the length of wire in the magnetic field, B=the flux desity) (v=velocity)
F ILB L F qvB ===Elements of Electronics
Capacitors and Capacitance Q=CV
6110farad microfarads =2
2
21potential energy=2
111..222CV Q P E CV QV C
===Photons, Atoms, Nuclei
2
kinetic energy
Planck's constant
momentum of the photon=wavelength
k k E hf W
E h
p h
mv
E mc λ
λ=-====
Special Relativity L L t m ==
=