A ring has a mass $M$ and radius $R$. The distance of the point on its geometric axis from its centre at which the gravitational field is strongest is

Statement I The force of attraction due to a hollow spherical shell of uniform density on a point mass situated inside it is always positive.

Statement II The force of attraction between a hollow spherical shell of uniform density and a point mass situated outside is same just as, if the entire mass of the shell is at the centre of the shell.

Which of the following is correct?

Let the escape speed of an object on the earth's surface be $v_0$. The object is projected out with speed $5 v_0$. The speed of the object far away from the earth will be

Four particles each of mass $m$ are placed at four vertices of a rectangle having side length as $3 l_0$ and $4 l_0$. The potential energy of the system in $\frac{G m^2}{l_0}$ is