Page 250 - Fisika Terapan for Engineers and Scientists

450 CHAPTER 14 Statics and Elasticity

SUMMARY

PROBLEM-SOLVING TECHNIQUES Static Equilibrium (page 437)

STATIC EQUILIBRIUM The sums of the external forces F F F 0 (14.1)
3
1
2
and of the external torques on a rigid body are zero.
T T T 0 (14.2)
1 2 3
STATICS CALCULATION TECHNIQUE To eliminate
an unknown force, evaluate torques about the point
where that force acts (or about another point where
the force has zero moment arm).

TORQUE DUE TO GRAVITY Gravity effectively
acts at the center of mass.

w

MECHANICAL ADVANTAGE OF LEVER F l

F l (14.15)
l
F l'

F'

BLOCK AND TACKLE An arrangement of several
pulleys that provides a mechanical advantage FFF
(equal to the ratio of the distance moved where the
force is applied to the distance moved by the load).

F'

PRESSURE F (14.21)
[pressure]
A