A cannon of mass M starts sliding freely down a smooth inclined plane at an angle `alpha` to the horizontal. After the cannon covered the distance `l`, a shot was fired, the shell leaving the cannon in the horizontal direction with a momentum p. As a consequence, the cannon stopped. Assuming the mass of the shell to be negligible, as compared to that of cannon, determine the duration of the shot.

Answer

`"["(t=Pcosalpha-msqrt(2glsinalpha))/(mgsinalpha)"]"`