Question

A rod is placed inside a hollow spherical shell as shown in figure. Friction acts between the rod and the shell. The number of forces to be shown in FBD of rod is/are?

• A. $3$
• B. $4$
• C. $5$
• D. $6$

Answer 1

The correct option is C $5$

Note that the direction of both normal reactions is along the radius of the sphere and the direction of forces are along the tangent. From the figure, we can see that the rod has a tendency to slip such that point $B$ comes down along the sphere and point A goes up. Hence, the direction of forces at $A$ and $B$ in both cases acts opposite to the tendency of slipping.