A string \(ABC\) (\(AB=BC=a\)) is stretched out straight on a smooth table with masses \(m\) tied at \(A, B, C\). Impulses each equal to \(I\) perpendicular to the string are applied at \(A\) and \(C\). Find the tensions just before \(A\) and \(C\) collide.
A particle projected with speed \(u\) strikes at right angles a plane through the point of projection inclined at \(\theta\) to the horizon; find the time of flight and the vertical height of the point struck above the point of projection.