A girl holds a book of mass `m` against a vertical wall with a horizontal force `F` using her finger so that the book does not move. The frictional froce on the book by the wall is :

An object of mass m held against a vertical wall by applying horizonatal force F as the minimum of the force is

An object of mass m held against a vertical wall by applying horizontal force F as shown in the figure . The minimum value of the force F is

A block of mass 'M' is pressed against a wall with a horizontal force F. Then a) it will slide down if the wall is smooth b) frictional force may balance the weight if the wall is rough c) Normal reaction is equal to weight of the block d) Normal reaction is zero if the wall is smooth

A block of mass 'M' is pressed against a wall with a horizontal force F. Then a) it will slide down if the wall is smooth b) frictional force may balance the weight if the wall is rough c) Normal reaction is equal to weight of the block d) Normal reaction is zero if the wall is smooth

A girl press her physics text book against a rough vertical wall with her hand. The direction of the frictional force on the book exerted by the wall is