Four solid spheres are made to move on a rough horizontal surface. Sphere `P` is given a spin and released. Sphere `Q` is given a forward linear velocity. Spheres `R` and `S` are given linear and rotational motions as shown in the figure. Directions of the friction force on spheres `P,Q,R,S` are respectively.
.

Options

A. Right, Left, Right, Left
B. Right, Left, Left, Right
C. Left, Right,Left, either Left or Right
D. Right, Left,Left,either Left or Right

Answer

D

Explanation

(d) In sphere `P`, the point of contact has tendency to move towards left w.r.t. surface and hence, friction acts on it towards right.
in spheres `Q` and `R`, the point of contact has tendency to move towards right w.r.t. surface and hence, friction acts on both of them towards left.
In sphere `S`, the point of contact has tendency to move towards left due to rotation and towards right due to translator motion. It has not been specified in question whether `v` is less than or greater than `omega R`. hence, friction on it may act towards left or right