$A$ spring-block system is placed on a rough horizontal floor. The block is pulled towards the right to give the spring some elongation and then released.

$A$ ball rests upon a flat piece of paper on a table top. The paper is pulled horizontally but quickly towards the right as shown. Relative to its initial position with respect to the table,the ball:
$(A)$ Remains stationary if there is no friction between the paper and the ball.
$(B)$ Moves to the left and starts rolling backwards,$i.e.$,to the left if there is friction between the paper and the ball.
$(C)$ Moves forward,$i.e.$,in the direction in which the paper is pulled.
Which of the following statements is/are correct?

$Assertion$: Use of ball bearings between two moving parts of a machine is a common practice.
$Reason$: Ball bearings reduce vibrations and provide good stability.

$A$ block $A$ of mass $m_1$ rests on a horizontal table. $A$ light string connected to it passes over a frictionless pulley at the edge of the table,and from its other end,another block $B$ of mass $m_2$ is suspended. The coefficient of kinetic friction between the block $A$ and the table is $\mu_k$. When the block $A$ is sliding on the table,the tension in the string is:

Find the accelerations $a_1, a_2$ and $a_3$ of the blocks if a $10\,N$ force $F$ is applied on the $3\,kg$ block as shown in the figure.

Three forces $F_1=10\,N$,$F_2=8\,N$,and $F_3=6\,N$ are acting on a particle of mass $5\,kg$. The forces $F_2$ and $F_3$ are applied perpendicular to each other such that the particle remains at rest. If the force $F_1$ is removed,then the acceleration of the particle is $......\,m/s^2$.