The restoring force of a spring with a block attached to the free end of the spring is represented by

A football of radius $R$ is kept on a hole of radius $r (r < R)$ made on a plank kept horizontally. One end of the plank is now lifted so that it gets tilted making an angle $\theta$ from the horizontal as shown in the figure below. The maximum value of $\theta$ so that the football does not start rolling down the plank satisfies (figure is schematic and not drawn to scale) -

In the figure shown, a balloon is pressed against a wall. It is in equilibrium and maximum compresed state.$\vec F_1\,=$ force of balloon on hand of man $;$  $\vec F_2\,=$  force of balloon on wall $;$  $\vec F_3\,=$ friction $;$ $\vec F_4=$  weight of balloon. Choose the correct statement.

Find wrong statement

A uniform rope of mass $M$ and length $L$ is fixed at its upper end vertically from a rigid support. Then the tension in the rope at the distance $l$ from the rigid support is $x$

In Newtonian mechanics which parameter apply external force ?