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