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 v

^{2}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 c

^{2}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 = R**

_{1}+ R_{2}resistances in series add together
1 / R = 1 / R

_{1}+ 1 / R_{2}reciprocals of resistances in parallel add together
I = I

_{1}+ I_{2}currents in parallel add together
I

_{in}= I_{out}total current into a point = total current out of a point
V = V

_{1}+ V_{2}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

__V___{p}=__N___{p}__voltage in primary coil__=__number of turns in primary coil__**V**

_{s}= N_{s}voltage in secondary coil number of turns in secondary coil
V

_{p}x I_{p}= V_{s}x I_{s}power in primary coil = power in secondary coil (for a perfect transformer)
Geometry

__Formula in Symbols__

__Formula in Words__

a = s

^{2}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 r

^{2}area of a circle = Pi x radius squared
v = s

^{3}volume of cube = length of side cubed
v = l x w x h volume
of cuboid = length x width x height

v = p x r

^{2}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.