a
Acceleration
A
Amplitude
d
Distance
E
Energy
f
Frequency
F
Force
I (uppercase)
Rotational inertia
K
Kinetic energy
k
Spring constant
L
Angular momentum
l (lowercase)
Length
m
Mass
P
Power
p
Momentum
r
Radius or separation
T
Period
t
Time
U
Potential energy
V
Volume
v
Speed
W
Work done on a system
x
Position
y
Height
α (alpha, lowercase)
Angular acceleration