Physics By BLIndo

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Wednesday, June 20, 2012


General Physics
Formula in Symbols            Formula in Words
v = d / t                                  speed = total distance / total time
w = m x g                              weight = mass x acceleration of gravity
a = v / t                                  acceleration = change in speed / change in time
d = m / v                                density = mass / volume
F = m x a                               force = mass x acceleration
x = k x F                                extension = a constant x load
W = F x d                               work = force x distance
p.e. = m x g x h                     potential energy = mass x acceleration of gravity x height
k.e. = ½ x m x v2                  kinetic energy = ½ x mass x velocity squared
e = Eout / Ein x 100%         energy efficiency = energy output / energy input x 100%
E = W                                    energy used = work done
E = m x c2                              energy of a nuclear reaction = mass x speed of light squared
P = E / t                                  power = energy / time

Physics of Waves
Formula in Symbols            Formula in Words
c = f x l                                 speed of a wave = frequency x wavelength
i = r                                        angle of incidence = angle of reflection
n = sin i / sin r                        index of refraction = sine of incident angle / sine of refracted angle

Electricity and Magnetism
Formula in Symbols            Formula in Words
I = Q / t                                  current = charge / time
R = V / I                 resistance = potential difference / current
R = k x l / A                           resistance = a constant x length / cross sectional area
R = R1 + R2                            resistances in series add together
1 / R = 1 / R1 + 1 / R2           reciprocals of resistances in parallel add together
I = I1 + I2                                currents in parallel add together
Iin = Iout                   total current into a point = total current out of a point
V = V1 + V2                            voltage of source = sum of all voltage drops in a circuit
P = I x V                                power used in an electric circuit = current x voltage
E = I x V x t                          energy used in an electric circuit = current x voltage x time
Vp = Np                   voltage in primary coil                    =   number of turns in primary coil
Vs = Ns                                    voltage in secondary coil                      number of turns in secondary coil
Vp x Ip = Vs x Is                     power in primary coil = power in secondary coil (for a perfect transformer)

Geometry
Formula in Symbols            Formula in Words
a = s2                                      area of a square = length of side squared
a = l x w                                 area of a rectangle = length x width
a = ½ x b x h                         area of a triangle =  ½ x base x height
a = p x r2                                area of a circle = Pi x radius squared
v = s3                                      volume of cube = length of side cubed
v = l x w x h                          volume of cuboid = length x width x height
v = p x r2 x h                         volume of cylinder = Pi x radius squared x height

You should be able to solve equations with three variables for any variable. 
For example, if a = b x c, then b = a / c and c = a / b.
Formulas in bold are for core.  Other formulas are extended, but they also help for many core questions.