$A$ body is imparted motion from rest to move in a straight line. If it is then obstructed by an opposite force,then:

$A$ balloon with mass $m$ is descending down with an acceleration $a$ (where $a < g$). How much mass should be removed from it so that it starts moving up with an acceleration $a$?

$A$ car accelerates on a horizontal road due to the forces exerted by

What is the value of the contact force $R$ on an object of mass $m$ placed on an inclined plane with angle $\theta$?

$A$ 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:
$(1)$ remains stationary if there is no friction between the paper and the ball.
$(2)$ moves to the left and starts rolling backwards,i.e.,to the left,if there is friction between the paper and the ball.
$(3)$ moves forward,i.e.,in the direction in which the paper is pulled.
Here,the correct statement$(s)$ is/are:

In the figure,two blocks $M$ and $m$ are tied together with an inextensible and light string. The mass $M$ is placed on a rough horizontal surface with coefficient of friction $\mu$ and the mass $m$ is hanging vertically against a smooth vertical wall. The pulley is frictionless. Choose the correct statement$(s)$ related to the tension $T$ in the string.