Projectile motion. how long does it take for the projectile to git the ground?

[hello_there]

I have no idea on where to start with this. Also we are not allowed to use The normal physics equations, we have to use maths.

At time t = 0 a projectile is fired from a height of h above level ground at an elevation angle
of a and a speed of v.

Show that the time when the projectile hits the ground will be
t =(vsin(a) + Sqrt( v²sin²(a) + 2hg))/g


thanks

 

[fzero]

Also we are not allowed to use The normal physics equations, we have to use maths.

Can you elaborate on this? It's obviously impossible to solve the problem without incorporating the acceleration due to gravity.

 

[hello_there]

we we told we can't use the equations like v=u+at and v^2= u^2 + 2as to work it out

 

[fzero]

Hmmm, are you allowed to use the fact that the trajectory is a quadratic equation? It's hard to guess what's allowed without knowing what was presented in class. Is there an allowed equation that contains the gravitational acceleration g?

 

[hello_there]

i guess we have to use a quadratic equation or there would be no way to do it, I'm just not sure how to incorperate g into the equation