$A$ tap can be easily opened or closed with the help of two fingers because:

For a particle moving in a circular path under the influence of a central force,the angular momentum remains constant because .......

Part of the tuning arrangement of a radio consists of a wheel which is acted on by two parallel constant forces as shown in the figure. If the wheel rotates just once, the work done will be about (diameter of the wheel = $0.05\ m$). (in $J$)

$A$ force $F_1 = A \hat{j}$ is applied to a point whose radius vector is $r_1 = a \hat{i}$, while a force $F_2 = B \hat{i}$ is applied to the point whose radius vector is $r_2 = b \hat{j}$. Both the radius vectors are determined relative to the origin of the coordinate axes $O$. The moment of the force relative to $O$ is

$A$ force of $(2\hat i - 4\hat j + 2\hat k) \ N$ acts at a point $(3\hat i + 2\hat j - 4\hat k) \ m$ from the origin. The magnitude of torque is ......... $N-m$.

$A$ force of $3\hat{i} + 2\hat{j} - \hat{k} \text{ N}$ acts on a particle with position vector $\hat{i} + \hat{j} - \hat{k} \text{ m}$. The magnitude of torque of the given force is