Question

A force with components (-7, 4, 5) acts at the point (2, 4, -3). Find the magnitude of moment about the origin.

• A. 10 units
• B. 13 units
• C. 16 units
• D. None of these

Answer 1

The correct option is D None of these

Here force is:

$F=-7\hat{i}+4\hat{j}+5\hat{k}$ and position of the point is: $r=2\hat{i}+4\hat{j}-3\hat{k}$.

The magnitude of moment about the origin will be: $=|r\times F|=|32\hat{i}+11\hat{j}+36\hat{k}|\simeq 49$