Symbol

Name

Definition

Unit(s)

Metric

English

a

a

Acceleration, linear

m/s²

ft/s²

g

g

Acceleration, due to gravity

32.26 ft/sec²

g₀

g₀

Pound force, 32.17 ft/sec²

32.17 ft/sec²

k

k

Radius of Gyration

m

m

Mass

n

n

Revolutions per unit of time

r

r

Radius

t

t

time

A

A

Area

cm²

ft²

D

D

Diameter

E

E

Modulus of Elasticity

E_K

E_K

Kinetic Energy

F

F

Force

newton

lbf

HP

HP

Power

ft lb / sec

I

I

Gear durability factor

I

I

Moment of Inertia

J

J

Inertia, polar (area) moment of

J

J

Gear strength factor

J_M

J_M

Moment of inertia about the axis of rotation

Kg·m²

lb-ft-sec² 

RPM

Rotational speed

revs/min

L

L

Angular momentum

M

M

Moment

lb-ft

P

P

Power

N·m

ft lb / sec

SHP

SHP

Shaft Horsepower

ft lb / sec

Q

Q

Torque

N·m

lbf-ft

W

W

Weight or Load

Z

Z

Section Modulus

α

alpha

Twist angle of joint

degrees

α

alpha

Acceleration, Angular

rad/sec²

β

Beta

Deflection angle of joint

degrees

ω

omega

Velocity, Angular, Angular frequency, Angular speed

rad·s^-1 or rad/sec

Ω

Omega

Rotational speed

rad/sec

τ

tau

Torque

N·m

lbf·ft