A child weighing $25 \,kg$ slides down a rope hanging from a branch of a tall tree. If the force of friction acting against him is $200 \,N$, the acceleration of child is ........... $m / s^2$ $\left(g=10 \,m / s ^2\right)$
$22.5$
$8$
$5$
$2$
Which of the following is a self adjusting force?
Two blocks $A$ and $B$ of masses $5 \,kg$ and $3 \,kg$ respectively rest on a smooth horizontal surface with $B$ over $A$. The coefficient of friction between $A$ and $B$ is $0.5$. The maximum horizontal force (in $kg$ wt.) that can be applied to $A$, so that there will be motion of $A$ and $B$ without relative slipping, is
A particle is moving along the circle $x^2 + y^2 = a^2$ in anti clock wise direction. The $x-y$ plane is a rough horizontal stationary surface. At the point $(a\, cos\theta , a\, sin\theta )$, the unit vector in the direction of friction on the particle is:
A bag is gently dropped on a conveyor belt moving at a speed of $2\,m / s$. The coefficient of friction between the conveyor belt and bag is $0.4$ Initially, the bag slips on the belt before it stops due to friction. The distance travelled by the bag on the belt during slipping motion is $.....m$ [Take $g=10\,m / s ^{-2}$ ]
What is the acceleration of the block and trolley system shown in a Figure, if the coefficient of kinetic friction between the trolley and the surface is $0.04$? What is the tension in the string ? (Take $g = 10\; m s^{-2}$). Neglect the mass of the string.