First slide

Torque

Question

A force of - F $\hat{k}$ acts on O, the origin of the coordinate system. The torque about the point (1, - 1) is

Moderate

A

F( $\hat{i} - \hat{j}$ )
B

-F ( $\hat{i} + \hat{j}$ )
C

F( $\hat{i} + \hat{j}$ )
D

-F( $\hat{i} - \hat{j}$ )

Solution

We know that
$\vec{τ} = \vec{r} \times \vec{F}$
The force F and point (1, - 1) is shown in figure.
Now
$\begin{array}{l} \vec{τ} = (\hat{i} - \hat{j}) \times (- F \hat{k}) \\ = F [(- \hat{i} \times \hat{k}) + (\hat{j} \times \hat{k})] \\ = F [\hat{j} + \hat{i}] = F (\hat{i} + \hat{j}) \end{array}$

Get Instant Solutions

When in doubt download our app. Now available Google Play Store- Doubts App

Recieve an sms with download link

Doubts App

OR

SCAN ME

Doubts App

Doubts App