For the given statements:
($$I.$$) $$\,\,\,$$ Mating spur gear teeth is an example of higher pair
($$II.$$) $$\,\,\,$$ A revolute joint is an example of lower pair.

Indicate the correct answer.

A rigid link PQ is 2 m long and oriented at 20^o to the horizontal as shown in the figure. The magnitude and direction of velocity V_Q, and the direction of velocity V_P are given. The magnitude of V_P(in m/s) at this instant is

A circular object of radius r rolls without $$V$$ slipping on a horizontal level floor with the center having velocity $$V.$$ The velocity at the point of contact between the object and the floor is

A planar closed kinematic chain is formed with rigid links $$PQ = 2.0 m, QR = 3.0 m, RS = 2.5 m$$ and $$SP = 2.7 m$$ with all revolute joints. The link to be fixed to obtain a double rocker (rocker-rocker) mechanism is