A pen of mass $m$ is lying on a piece of paper of mass $M$ placed on a rough table. If the coefficients of friction between the pen and paper and the paper and the table are $\mu_1$ and $\mu_2$, respectively. Then, the minimum horizontal force with which the paper has to be pulled for the pen to start slipping is given by
$(m+M)\left(\mu_1+\mu_2\right) g$
$\left(m \mu_1+M \mu_2\right) g$
$\left(m \mu_1+(m+M) \mu_2\right) g$
$m\left(\mu_1-\mu_2\right) g$
A block of mass $2 \,kg$ rests on a rough inclined plane making an angle of $30°$ with the horizontal. The coefficient of static friction between the block and the plane is $ 0.7$. The frictional force on the block is ....... $N$.
A block of mass $15 \;kg$ is placed on a long trolley. The coefficient of static friction between the block and the trolley is $0.18$. The trolley accelerates from rest with $0.5 \;m s ^{-2}$ for $20 \;s$ and then moves with uniform velocity. Discuss the motion of the block as vlewed by
$(a)$ a stationary observer on the ground,
$(b)$ an observer moving with the trolley.
The frictional force acting on $1 \,kg$ block is .................. $N$
A heavy uniform chain lies on a horizontal table-top. If the coefficient of friction between the chain and table surface is $0.25$, then the maximum fraction of length of the chain, that can hang over one edge of the table is ...... $\%$
A small body slips, subject to the force of friction, from point $A$ to point $B$ along two curved surfaces of equal radius, first along route $1,$ then along route $2$. Friction does not depend on the speed and the coefficient of friction on both routes is the same. In which case will the body’s speed at $B$ be greater?