Question

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

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

Answer 1

The correct option is C $C$

Moment is defined as $r\times F$

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

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

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

Hence moment about O for C is less.