Page 209 - Dynamics of Mechanical Systems

0593_C06_fm Page 190 Monday, May 6, 2002 2:28 PM

190 Dynamics of Mechanical Systems

a. Determine the resultant R of this system of forces.
b. Find the moments of the force system about points C, H, E, and G.

Express the results in terms of the unit vectors n , n , and n shown in Figure P6.3.3.
2
1
3
TABLE P6.3.3
Forces, Their Magnitudes, and Lines of Action for the Force
System of Figure P6.3.3
Force Magnitude (lb) Line of Action
10 AB
F 1
10 GH
F 2
8 CB
F 3
8 GD
F 4
12 CD
F 5
12 EO
F 6
6.4 Special Force Systems: Zero Force Systems and Couples
P6.4.1: In Figure P6.4.1, the box is subjected to forces as shown. The magnitudes and
directions of the forces are listed in Table P6.4.1. Determine the magnitudes of forces F ,
1
F , F , F , F , and F so that the system of forces on the box is a zero system.
10
3
6
5
4
n
A 3 E
F
F 6
B 7 D
F F 11
8
3m
F O G
1 F
5
4m
C H n 2
12m
n F
1 3 F F 9
F 4
FIGURE P6.4.1 10 F
2
Force system exerted on a box.
TABLE P6.4.1
Forces, Their Magnitudes, and Lines of Action
for the Forces of Figure P6.4.1
Force Magnitude (N) Line of Action
10 AB
F 1
8 CB
F 2
8 AO
F 3
6 HG
F 4
7 GO
F 5
5 AE
F 6
10 GD
F 7
16 DB
F 8
12 HD
F 9
9 CO
F 10
26 OD
F 11