4.96 NICHOLLS'S SEAMANSHIP AND NAUTICAL KNOWLEDGE

DE

20/1$
Fig. 14.

The distance of the centre of gravity (C. of G ) of the system from A,

Moment 160
neglecting the weight of the batten, is . =='on === J which is

obvious as the weight B could be suspended in equilibrium by a cord G
if the pivot at A were withdrawn.

(ii) Distribution of Weights.—Suspend a 10 Ib. weight at C 6 feet
from A, and another 10 Ib. weight at B 8 feet from A. Then moment
about A=(Q ft. X10 lbs.)+(8 ft. XlO lbs.)=140 foot-lbs. The bending
moment at A is now 140 foot-lbs. as against 160 foot-lbs. in example
(i), 20 foot-lbs. less, although the total weight suspended by the rod
(20 Ibs.) is the same, its distribution, however, is different (Figure 15),

G

A

i

Fig 15.
Moment about A 140
The C. of G. of the system =———;-----—-----=-—=7 feet from A.
Total weight 20
ind if the pivot at A were removed the system could be balanced in
equilibrium at 0 midway between the two 10 Ib. weights, which is
obvious when the weight of the rod ia neglected.
(iii) Redistribution of Weights.—Suspend four 5 Ibs. weights at B, C, D
and E> points which are 8, 6, 4 and 2 feet from A respectively. Tbie
moment about A is now (8x5)+t6x5)+(4x5)+(ax5)=100foot-lbk