Question

$A,B$ and $C$ are the three forces each of magnitude $4N$ acting in the plane of paper as shown in Fig. The point $O$ lies in the same plane. Which force has the greatest moment about $O$?

• A. $A$
• B. $B$
• C. $C$
• D. all of the above

Answer 1

The correct option is A $A$

Moment is defined as $r\times F$

Here r is the perpendicular distance from the force to that point O.

Given the perpendicular distances 0.9 m, 0.8m, 0.6m for forces A,B,C of the same magnitude 4 N. Hence,

For A
$moment=0.9\times 4=3.6Nm$
For B
$moment=0.8\times 4=3.2Nm$
For C
$moment=0.6\times 4=2.4Nm$.

Hence moment of force A about O is largest.