INTRODUCTION TO DESIGN

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1

 

Table 1-4 Variables and Units

Base Units in Boldface - Abbreviations in ( )

Variable

Symbol

ips unit

fps unit

SI unit

 

Force

F

pounds (lb)

pounds (lb)

newtons (N)

Length

l

inches (in)

feet (ft)

meters (m)

Time

t

seconds (sec)

seconds (sec)

seconds (sec)

Mass

m

lb-sec2/in (bl)

lb-sec2/ft (sl)

kilograms (kg)

Weight

W

pounds (lb)

pounds (lb)

newtons (N)

Pressure

p

psi

psf

N/m2 = Pa

Velocity

v

in/sec

ft/sec

m/sec

Acceleration

a

in/sec2

ft/sec2

m/sec2

Stress

 

psi

psf

N/m2 = Pa

Angle

degrees (deg)

degrees (deg)

degrees (deg)

Angular velocity

radians/sec

radians/sec

radians/sec

Angular acceleration

radians/sec2

radians/sec2

radians/sec2

Torque

T

lb-in

lb-ft

N-m

Mass moment of inertia

I

lb-in-sec2

lb-ft-sec2

kg-m2

Area moment of inertia

I

in4

ft4

m4

Energy

E

in-lb

ft-lb

joules = N-m

Power

P

in-lb/sec

ft-lb/sec

N-m/sec = watt