$A$ block is placed on a rough horizontal plane. $A$ time-dependent horizontal force $F = Kt$ acts on the block,where $K$ is a positive constant. The acceleration-time graph of the block is:

Two bodies $A$ and $B$ of masses $5 \, kg$ and $10 \, kg$ in contact with each other rest on a table against a rigid wall. The coefficient of friction between the bodies and the table is $0.15$. $A$ force of $200 \, N$ is applied horizontally to $A$. What are $(a)$ the reaction of the partition $(b)$ the action-reaction forces between $A$ and $B$? What happens when the wall is removed? Does the answer to $(b)$ change,when the bodies are in motion? Ignore the difference between $\mu_{s}$ and $\mu_{k}$.

Two fixed frictionless inclined planes making an angle $30^\circ$ and $60^\circ$ with the vertical are shown in the figure. Two blocks $A$ and $B$ are placed on the two planes. What is the relative vertical acceleration of $A$ with respect to $B$?

$A$ car is moving with uniform velocity on a rough horizontal road. Therefore,according to Newton's first law of motion,

$A$ spring-block system is placed on a rough horizontal floor. The block is pulled towards the right to give the spring an elongation $x_0$ such that $\frac{\mu mg}{K} < x_0 < \frac{2\mu mg}{K}$,and then released. Which of the following statements is correct?

$A$ truck of mass $M$ is at rest on a frictionless road when a monkey of mass $m$ starts moving on the truck in the forward direction. If the truck recoils with a speed $v$ backward on the road,with what velocity is the monkey moving with respect to the truck?