A wagon is accelerating to the right. A book is pressed against the back vertical side of the wagon. The coefficient of static friction between the book and the vertical back of the wagon is μs.

The coefficient of static friction between the book and the vertical back of the wagon is

Explanation:

Since the book is pressed against the vertical side of the wagon, the weight of the book will be acting downwards. i.e.

Let the frictional force between the book and the vertical back of the wagon be

For the book not to drop down from the back vertical side of the wagon,

........................(1)

A static frictional force is given as ............(2)

where N= Normal Reaction

Equating (1) and (2)

80cm/s.

24cm/s.

53.3cm/s.