A block of $1\, kg$ is stopped against a wall by applying a force $F$ perpendicular to the wall. If $\mu = 0.2$ then minimum value of $F$ will be ....... $N.$

Which one of the following is not used to reduce friction

A block of mass $m$ is moving with a constant acceleration a on a rough plane. If the coefficient of friction between the block and ground is $\mu $, the power delivered by the external agent after a time $t$ from the beginning is equal to

Two beads connected by massless inextensible string are placed over the fixed ring as shown in figure. Mass of each bead is $m$ , and there is no friction between $B$ and ring. Find minimum value of coefficient of friction between $A$ and ring so that system remains in equilibrium. ( $C \to $center of ring, $AC$ line is vertical)

A block of mass $10\, kg$ moving at $10\,m/s$ is released to slide on rough surface having  coefficient of friction $0.2.$ It will stop by travelling distance ........ $m$

In the figure, a ladder of mass $m$ is shown leaning against a wall. It is in static equilibrium making an angle $\theta$ with the horizontal floor. The coefficient of friction between the wall and the ladder is $\mu_1$ and that between the floor and the ladder is $\mu_2$. The normal reaction of the wall on the ladder is $N_1$ and that of the floor is $N_2$. If the ladder is about to slip, then

$Image$

$(A)$ $\mu_1=0 \mu_2 \neq 0$ and $N _2 \tan \theta=\frac{ mg }{2}$

$(B)$ $\mu_1 \neq 0 \mu_2=0$ and $N_1 \tan \theta=\frac{m g}{2}$

$(C)$ $\mu_1 \neq 0 \mu_2 \neq 0$ and $N _2 \tan \theta=\frac{ mg }{1+\mu_1 \mu_2}$

$(D)$ $\mu_1=0 \mu_2 \neq 0$ and $N _1 \tan \theta=\frac{ mg }{2}$