A $1.0 kg$ block of wood sits on top of an identical block of wood, which sits on top of a flat level table made of plastic. The coefficient of static friction between the wood surfaces is $\mu_1$, and the coefficient of static friction between the wood and plastic is $\mu_2$. Ahorizontal force $F$ is applied to the top block only, and this force is increased until the top block starts to move. The bottom block will move with the top block if and only if
$\mu_1 < \frac{1}{2}{\mu _2}$
$\frac{1}{2}{\mu _2} < \mu_1 < \mu_2$
$\mu_2 < \mu_1$
$2\mu_2 < \mu_1$
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
......... $m/s^2$ is magnitude of acceleration of a block moving with speed $10\,m/s$ on a rough surface if coefficient of friction is $0.2$.
A horizontal force $12 \,N$ pushes a block weighing $1/2\, kg$ against a vertical wall. The coefficient of static friction between the wall and the block is $0.5$ and the coefficient of kinetic friction is $0.35.$ Assuming that the block is not moving initially. Which one of the following choices is correct (Take $g = 10 \,m/s^2$)
A block pressed against the vertical wall is in equilibrium. The minimum coefficient of friction is:-
Write unit of coefficient of static friction.