A girl holds a book of mass m against a vertical wall with a horizontal force F using her finger, so

English

Gujarati

Hindi

4-2.Friction

medium

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 force on the book by the wall is

A

$F$ and along the finger but pointing towards the girl

B

$\mu F$ upwards, where $\mu$ is the coefficient of static friction

C

$m g$ and upwards

D

equal and opposite to the resultant of $F$ and $m g$

(KVPY-2012)

Solution

(b)

Minimum force $F$ must be such that generated friction is able to balance weight $m g$ of book.

So, $\quad f=\mu N=\mu F$.

Standard 11

Physics

Share

Similar Questions

Among the forces in nature, friction can be classified into

medium

The force acting on the block pushes it, then pushing of the block will be possible along the surface if

medium

Why are mountain roads generally made winding upwards rather than going straight up ?

easy

A board is balanced on a rough horizontal semicircular log. Equilibrium is obtained with the help of addition of a weight to one of the ends of the board when the board makes an angle $\theta$ with the horizontal. Coefficient of friction between the log and the board is

hard

A block of mass $1\, kg$ is at rest on a horizontal table. The coefficient of static friction between the block and the table is $0.5.$ The magnitude of the force acting upwards at an angle of $60^o$ from the horizontal that will just start the block moving is

medium