Answer:
[tex]y = \frac{2v^2g}{a^2}[/tex]
Explanation:
Since fire cracker land at the position just below the student
so we can say that the displacement in X direction must be zero
so we will have
[tex]\Delta x = v_x t + \frac{1}{2}a_x t^2[/tex]
[tex]0 = v t - \frac{1}{2}at^2[/tex]
[tex]t = \frac{2v}{a}[/tex]
now in the same time it travels in y direction
so the displacement is given as
[tex]y = \frac{1}{2}gt^2[/tex]
[tex]y = \frac{1}{2}g(\frac{2v}{a})^2[/tex]
[tex]y = \frac{2v^2g}{a^2}[/tex]