Question

A body is under the action of three forces $\overrightarrow{F_1},\overrightarrow{F_2}$ and $\overrightarrow{F_3}$. In which case the body cannot undergo angular acceleration?

• A. $\overrightarrow{F_1},\overrightarrow{F_2}$ and $\overrightarrow{F_3}$ are concurrent
• B. $\overrightarrow{F_1}+\overrightarrow{F_2}+\overrightarrow{F_3}=0$
• C. $\overrightarrow{F_1},\overrightarrow{F_2}$ is parallel to $\overrightarrow{F_3}$ but the three forces are not concurrent
• D. $\overrightarrow{F_1}$ and $\overrightarrow{F_2}$ act at the same point but $\overrightarrow{F_3}$ acts at different point.

Answer 1

The correct option is A $\overrightarrow{F_1},\overrightarrow{F_2}$ and $\overrightarrow{F_3}$ are concurrent

The body will not undergo angular acceleration only if all the forces acting on the body are in the same plane. In any other case, there will always be a component of force that is in a different plane and thus cannot be balanced. This component will always result in angular and linear acceleration