A clock has a continuously moving second's hand of length. The average acceleration of the tip of the hand (in
) is in the order of :
The uniform circular discs are rotating in the same direction around their common axis passing through their centres. The moment of inertia and angular velocity of the first disc are and
respectively, While those for the second one are
and
respectively. At some instant, they get stuck together and start rotating as a single system about their common axis with some angular speed. The kinetic energy of the combined system is
A force acts at a point
. Then the magnitude of torque about the point
will be
. The value of
is ________.