Common Physics Equations - StickMan Physics

Common Physics Equations

Variables: (mks unit)

Motion

????

????

?=

vave : average velocity (m/s)

??

=

?

¦¤x or x : change in position or displacement (m)

(?? + ?? )

=

?

¦¤t or t : change in time or time (s)

¦¤v : change in velocity (m/s)

?? (?? ? ?? )

=

?

?

vi : initial velocity (m/s)

vf : final velocity (m/s)

?? = ?? + ??

a : acceleration (m/s2)

??? = ??? + ????

?? = ?? ? + ?/? ???

? = (

(note: on many different equation sheets x is

substituted by d for displacement)

?? + ??

)?

?

Projectile Motion

X axis projectile equation

? = ?? ?

Variables (mks unit)

Y axis projectile equations

?

?? = ??? ? + ?/? ??

??? = ??? + ??

Note: the Y axis equations are the

same as the accelerated motion

equations above but specialized

for something in freefall along

the Y axis

???? = ???? + ????

? = ?. ? ?/??

Only if viy = 0

?? = ??? ? + ?/? ???

Becomes

? = ¡Ì(

???

)

?

¦¤y or y : change in position or

displacement (m) in the y axis

¦¤v : change in velocity (m/s)

Viy : initial Y axis velocity (m/s)

Vfy : final Y axis velocity (m/s)

g : acceleration due to gravity

(m/s2)

Variables (mks unit)

Force and Friction

¡Æ ? = ???? = ??

¡Æ ? ?? ???? ¡Ã ?????? ??? ?? ?????? (?)

m : mass (kg)

m1a1 = m2a2

?? = ??

a : acceleration (m/s2)

?? = ???

FW : weight (N)

?? = ???

Ff : Force of friction (N)

? : coefficient of friction (no unit)

Fs : Spring Force (N)

k : spring constant (N/m or kg/s2)

x: displacement of stretched spring (m)

Gravitation and Circular Motion

Fc : centripetal force (N)

?? = ???

ac : centripetal acceleration (m/s2)

???

?? =

?

?? =

v : velocity (m/s)

??

?

r : radius (m)

¦Ð : pie (3.14 rounded)

???

?=

?

?? =

Fg : Force of Gravity (N)

??? ??

??

? = ?. ????????

? = ?? ?

?? ?? = ?? ??

?=

?

?

?

?=

?

Variables (mks unit)

???

???

G : universal gravitation constant (

???

???

)

m1 : mass one (kg)

m2 : mass two (kg)

d : distance between objects (m)

? : Torque (Nm)

F?: Perpendicular Force (N)

T: Period (s)

f: Frequency (Hz)

F1 and F2 represent two different forces created by

object 1 or 2 (N)

d1 and d2 represent two different distances that

object one or two are from the fulcrum or

rotational point (m)

Energy and Momentum

Variables (mks unit)

PE = mgh

PE : potential energy (J)

KE = ? mv2

m : mass (kg)

PEi + KEi = PEf + KEf

g : acceleration due to gravity (m/s2)

mghi + ? mvi2 = mghf + ? mvf2

h : height (m)

P = mv

KE : kinetic energy (J)

Impulse = F¦¤t

v : velocity (m/s)

F¦¤t = ¦¤(mv)

p : momentum (kg?m/s)

J: Impulse (Ns)

Elastic Collisions

m1 : first objects mass (kg)

m1v1i + m2v2i = m1v1f+m2v2f

v1i : first objects initial velocity (m/s)

Inelastic Collisions

m2 : second mass (kg)

m1v1 + m2v2i = (m1 + m2)vf

v2i : second objects initial velocity (m/s)

-

v1f : first objects final velocity (m/s)

v2f : second object final velocity (m/s)

vf : combined final velocity (m/s)

Work and Power

Variables (mks unit)

W = F// d

W : work (J)

?=

?

?

P : power (W)

F// : Force parallel to the motion (N)

?// ?

?=

?

W = ¦¤KE

Variables (mks unit)

Simple Machines

??? =

???

????

??? =

????

???

?????????? =

IMA : Ideal Mechanical Advantage (none)

din : distance on input side (m)

dout : distance on output side (m)

????

???

X 100%

Fin : Force on input side (N)

Fout : Force on output side (N)

Fout is force provided by the machine and

equal to the weight you are trying to lift

Variables (mks unit)

Electricity

? ?? =

Fel : electrical force (N)

??? ??

??

???

?

? = ?. ????

??

?

? =

V = IR

?

?

? =

?

? =

?

?

?

? =

?

k : coulomb constant (

???

??

q : charge (C)

q1 or q2 : multiple objects with charge (C)

P = IV

d : distance between (m)

P = I2R

I : current (A)

??

? =

?

T: time (s)

? =

??????

?

qe : charge of electron

= -1.6 x 10-19 C

)

E : electrical field (N/C)

V : potential difference or voltage (V)

W : work (J)

P : power (W)

R : resistance (¦¸ or Ohms)

Series Circuit

Variables and Subscripts

???? = ?? + ?? + ?? + ?

Subscripts

?? = ?? = ?? = ?? = ?

?? = ?? + ?? + ?? + ?

Parallel Circuit

???? = ?? = ?? = ?? = ?

(1,2,3, ¡­): first, second, third resistor

or device, and so forth¡­

T or emf: equivalent or total

calculated at the battery or power

source

?? + ?? + ?? + ?? + ?

?

?

?

?

=

+

+

+?

?? ?? ?? ??

V : voltage (m/s)

At Device (more in last section)

R : resistance (¦¸ or Ohms)

? = ??

? = ??

I : Current (A)

Sound and Waves

Variables (mks unit)

? = ??

v : velocity (m/s)

?=

?=

?

?

f : frequency (Hz)

? : wavelength (m)

?

?

T : period (s)

Vsound : velocity of sound (m/s)

vsound= 331m/s + 0.6T(¡ãC)

Optics

Variables (mks unit)

? ?

?

= +

? ?? ??

f : focal length (m)

?=

di : distance to image (m)

?? ???

=

??

??

do : distance to object (m)

M : magnification (times)

nisin?i = nrsin?r

hi : height of image (m)

??

????? =

??

?=

ho : height of object (m)

?

n : index of refraction (no unit)

?????????

ni : index of refraction incident side (no unit)

c = 3x108 m/s

nr : index of refraction refracted side (no unit)

?i : angle of incidence (¡ã)

?r : angle of refraction (¡ã)

?c : critical angle (¡ã)

vmaterial : velocity of light in a material (m/s)

c : speed of light or any electromagnetic wave

in a vacuum (3x108 m/s)

Trig Reminders

?? = ?? + ??

???

???? = ???

???

???? = ???

???? =

???

???

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