Torque MCQ - Practice Questions with Answers

• The vector product of the Force vector and position vector is known as torque.
• - $\vec{\tau}=\vec{r} \times \underset{F}{\vec{F}}$
• - Its direction is always perpendicular to the plane containing vectors r and F and with the help of the right-hand screw rule we can find it.
• - The magnitude of torque is calculated by using either
• - $\tau=r_1 F$ or $\tau=r \cdot F_1$
• $r_1=$ perpendicular distance from the origin to the line of force.
• $F_1=$ component of force perpendicular to line joining force.
• - $\tau=r . F \cdot \sin \phi$
• Where $\phi$ is the angle between vector r and F
• - $\tau_{\text {max }}=r . F\left(\right.$ when $\left.\phi=90^0\right)$
• - $\tau_{\text {min }}=0\left(w h e n ~ \phi=0^0\right)$

•  If a pivoted, hinged body tends to rotate due to an applied force, then it is said that torque is acted on the body by force.

Example-

In the rotation of a hinged door when we apply torque with the help of force F.

- SI Unit- Newton-metre
- Dimension- $M L^2 T^{-2}$
- If a body is acted upon by more than one force, then we get the resultant torque by doing the Vector sum of each torque.

$$
\tau=\tau_1+\tau_2+\tau_3 \cdots \cdots
$$

- Just like force is the cause of translatory motion similarly Torque is the cause of rotatory motion.