500 NICE.OLLS S SEAMANSHIP AND NAUTICAL KNOWLEDGE

G.
*

sLl*

Fig. 21.

130
Distance K G, = —r = 5*2 feet

25

KG

=4-0

« 1-2

Adding the 10 Ibs. weight has shifted the C. of G. of the system 1-2
feet to the right.

Example. — A rod of wood AB is pivoted at
A so that it revolves freely in a vertical
plane. A 5 Ibs. weight is suspended at B, 8
feet from A, by means of a string over a
frictionless pulley C. What weight must
be suspended at D, 3 feet from A, by a string
through the pulley E to keep the rod per-
pendicular?

The left hand moment about A must be
made equal to the right hand moment about
A to maintain perpendicularity.

Therefore 3 ft. X TF=8 ft. x5 Ibs.
3 TF=40.'. IF

Answer. — 13J Ibs.