Formulas Flashcards

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1
Q

Power

A

Rate of work done

Power= Work/time Unit: Watt

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2
Q

Efficiency of Work

A

Work_out/Energy_in

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3
Q

Heating a solid, liquid, or gas formula

A
Q= m c ΔT
c= specific heat
Q= heat added
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4
Q

Linear Momentum

A

p=mv

Momentum is conserved in collisions

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5
Q

Centre of Mass

A

Point masses on a line

x_cm= Sum of (mx)/M_total

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6
Q

Pressure under Water

A
P= p g h
p = density of water
h= dept of water
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7
Q

Universal Gravitation

A
F= G (mm/r^2)
G= 6.67 x  10^-11 N m^2/kg^2
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8
Q

Mechanical energy

A
PE_grav= P = mgh
KE_linear= K = 1/2mv^2
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9
Q

Snell’s Law

A

n1sinθ=n2sin θ

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10
Q

Index of refraction

A

n=c/v

c= speed of light 3 x 10^8 m/s

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11
Q

Periodic Waves

A
v= f λ
f= 1/T 
T = period of wave
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12
Q

Bouyant Force

A
Fb= p V g = (m_displaced fluid)g = weight_displaced fluid
p= density of the fluid
V= Volume of the fluid
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13
Q

Ohm’s Law

A
V= IR
V= Voltage
I= current
R= resistance
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14
Q

Resistance of a Wire

A
R= p L / A_x
p= resistivity of wire material
L= length of the wire
A_x= cross sectional area
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15
Q

Heat of a phase change

A
Q= m L
L= latent heat of phase change
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16
Q

Hooke’s Law

A

F= k x
PE of spring
W= 1/2kx^2 = work done on spring

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17
Q

Electric Power

A

P = I^2R = V^2/R= IV

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18
Q

Speed of wave on string

A
T = mv^2/L
T = tension in string
m = mass of string
L = length of string
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19
Q

Projectile Motion

A

Horizontal: x-x_o = v_o t + 0
Vertical: y-y_o = v+o t + 1/2at^2

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20
Q

Centripetal Force

A

F= mv^2/r = mw^2r

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21
Q

Kirchhoff’s Law

A

Loop Rule: Sum_around any loop Δ V_i=0

Node rule: Sym_at any node I_i=0

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22
Q

Minimum speed at the top of a Vertical circular loop

A

v=Sqrt(rg)

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23
Q

Resistor Combos

A

Series: R_eq= R1+R2+R3….

Parallel = 1/R_eq

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24
Q

Newton’s second law and Rotation Inertia

A
τ = torque = I  α
I = moment of inertia = m r^2
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25
Q

Circular unbanked tracks

A

mv^2/r = umg

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26
Q

Continuity of fluid flow

A

A_in v_in = A_out v_out
A = Area
v= velocity

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27
Q

Moment of Inertia

A
Cylindrical hoop:   m r^2 para to hoop
Solid cylinder or disk: 1/2 m^2 para to disk
Sold sphere: 2/5 m r^2
hollow sphere: 2/3m r^2
Thin rod center: 1/12 m L^2 para to rod
Thin rod end 1/3 m L^2 para to rod
28
Q

Capacitors

A
Q= CV
Q= charge on capacitor
C= Capacitance
V= voltage applied
29
Q

Charging a capacitor

A
I(t) = I_o e ^(-t/RC)
Q(t) = Q_o e (1-e^(-t/RC))
e = 2.718
t = time since circuit change
R = resistance (Ohm)
C = capacitance (farad)
30
Q

Ohm

A

Volt/amp

31
Q

Farad

A

Coulomb/ Volt

32
Q

Thermal Expansion

A

Linear: ΔL = L_o alpha ΔT
Volume: ΔV = V_o beta ΔT

33
Q

Bernoulli’s Equation

A

P + p g h+ 1/2 pv^2= constant

Q_Volume Flow Rate= A1v1 = A2v2= constant

34
Q

Rotational KE

A

KE_rotational = 1/2 I w^2 = 1/2 I (v/r)^2

KE_ rolling w/o slipping = 1/2 mv^2 + 1/2 I w^2

35
Q

Angular Momentum = L

A

L= I w= m v r sin θ
Angular impulse equals change in Angular momentum
ΔL= torque Δt= Δ(I w)

36
Q

Period of Simple Harmonic Motion

A
T = 2 pi sqrt(m/k)
k = spring constant
f = 1/T = 1/period
37
Q

Banked Circular tracks

A

v^2 = r g tan θ

38
Q

First Law of Thermodynamics

A

ΔU = Qnet + W net
Change in Internal Energy of a system =
+ Net Heat added to the system
+ Work done on the system

39
Q

Flower of Heat through a Solid

A
ΔQ/Δt = (k A ΔT)/ L
k = thermal conductivity
A = area of solid
L = thickness of solid
40
Q

PE stored in Capacitor

A

P = 1/2 C V^2

41
Q

RC Circuit Formula (Charging)

A

V_e = V_cell (1-e^(-t/RC))
RC = time constant
V_cell- V_capacitor - IR = 0

42
Q

Simple Pendulum

A
T = 2pi sqrt (L/g) 
f = 1/T
43
Q

Sinusoidal motion

A
x= A cos (wt) = A cos (2pi f t)
w= angular frequency
f= frequency
44
Q

Doppler Effect

A
f' = f (343 (+_) v_o)/(343 (_+) v_s)
v_o= velocity of observer
v_s= velocity of source
45
Q

2nd Law of Thermodynamics

A

Change in internal energy of system is ΔU = Q added + W done on - Q lost - W done by

46
Q

Thin lens equation

A
1/f = 1/D_o + 1/D_i= 1/o +1/i 
f = focal length
i = image distance
o = object distance
Magnification:  M = -D_i/D_o = 
-i/o = H_i/H_o
47
Q

Mirrors and Lens: Positive focal length

A
Mirror : concave
Lens: converging
Object distance o = all objects 
Object height H_o= all objects
Image distance = i  real 
Image height = H_i virtual;upright
Magnification : Virtual; upright
48
Q

Mirrors and lens: Negative focal length

A
Mirror : convex
Lens: diverging
Object distance o = all objects 
Object height H_o= all objects
Image distance = i  Virtual 
Image height = H_i real;inverted
Magnification : Real; inverted
49
Q

Coulomb’s Law

A
F= k (qq/r^2)
k= 1/4piE_o = 9 x 10^9 N m^2/C^2
50
Q

Work done on a gas or by a gas

A

W= P Δ V

51
Q

Electric field around a point charge

A

E = k (q/r^2)

52
Q

Magnetic Field around a wire

A

B = (u_o I/ 2pir)

Magnetic Flux: B A Cos θ

53
Q

Force caused by a magnetic field on a moving charge

A

F= qvBsin θ

54
Q

Entropy change at a constant T

A

ΔS = Q/T

55
Q

Capacitance of Capacitor

A
C= K E_o A / d
K= dielectric constant
A= area of plates
d= distance between plates
E_o = 8.85 x 10^-12 F/m
56
Q

Induced Voltage

A

N= # of loops
Emf = N ΔΦ / Δt
Lenz’s Law - induced current flows to create a B field opposing the change in the magnetic flux

57
Q

Transformers

A
N1/N2 = V1/V2
I1V1 = I2V2
58
Q

Decibel Scale

A

B (decibel level of sound) = 10 log (I/I_o)
I = intensity of sound
I_o = intensity of soften audible sound

59
Q

Poiseuille’s Law

A
ΔP = 8 n L Q /(pir^4)
n = coefficient of viscosity
L= length of pipe
r = radius of pipe
Q = flow rate of fluid
60
Q

Stress and Strain

A
B = stress/strain
Stress = F/A
Unit less ratios
Linear: strain= ΔL / L
Shear: strain = Δx/ L
Volume: strain= ΔV/V
61
Q

Postulates of special relativity

A
  1. Absolute, uniform motion cannot be detected.

2. No energy or mass transfer can occur at speeds faster than the speed of light

62
Q

Energy of a photon

A
E = hf = mc^2
h= planck's constant = 6.64 x 10^-34 J s
f= frequency of the photon
63
Q

Radioactive Decay

A
A = A_o e ^(-kt) = (1/2^n) A_o
k = (ln2)/half life
64
Q

Early Quantum Physics

Rutherford Bohr H Atoms

A
1/λ = R (1/n^2 - 1/n^2) meters^-1
R= Rydberg's constant = 1.098 x 10^7 m^-1
65
Q

Mass Energy Equivalence

A

m_v = m_o/ Beta
Total Energy = KE + m_o c^2 = m_o c^2/ Beta
E = mc^2

66
Q

de Broglie Matter Waves

A
E_p = h f = h c/λ= pc
Momentum : p = h / λ
For particles, p = m v = h / λ
Matter wave's wavelength must be 
λ= h/ m v