Question 69 – Rankers Physics

Uncategorized: Practice Problem & Solution

If $\vec{F}$ is the force acting on a particle having position vector $\vec{r}$ and $\vec{\tau}$ be the torque of this force about the origin, then: (2009)
$\vec{r}\cdot\vec{F}>0$ and $\vec{F}\cdot\vec{\tau}<0$
$\vec{r}\cdot\vec{\tau}=0$ and $\vec{F}\cdot\vec{\tau}=0$
$\vec{\tau}\cdot\vec{\tau}=0$ and $\vec{F}\cdot\vec{\tau}\neq0$
$\vec{r}\cdot\vec{\tau}=0$ and $\vec{F}\cdot\vec{\tau}=0$

Solution Explained:

To solve this problem, we apply the core principles of Uncategorized. Understanding the underlying formula is key to arriving at the correct answer below:

Torque is defined as the cross product of position vector and force: $\vec{\tau} = \vec{r} \times \vec{F}$.
By the properties of cross products, the resulting vector $\vec{\tau}$ is perpendicular to both $\vec{r}$ and $\vec{F}$.
Therefore, their dot products must be zero: $\vec{r}\cdot\vec{\tau} = 0$ and $\vec{F}\cdot\vec{\tau} = 0$.

Leave a Reply

Your email address will not be published. Required fields are marked *