A football of radius R is kept on a hole of radius r (π < π ) made on a plank kept horizontally. One endΒ of the plank is now lifted so that it gets tilted making an angle π from the horizontal as shown in theΒ figure below. The maximum value of π so that the football does not start rolling down the plankΒ satisfies (figure is schematic and not drawn to scale) -
1
\(\rm \sin \theta=\frac{r}{R}\)
2
\(\tan \theta=\frac{\mathrm{r}}{\mathrm{R}}\)
3
\(\rm \sin \theta=\frac{r}{2 R}\)
4
\(\rm \cos \theta=\frac{r}{2 R}\)