Homework Help: Non-Horizontally launched Projectile

1. The problem statement, all variables and given/known data
A ball is thrown from the ground (height=0) with an initial speed Vo at an angle of 45 degrees

a)when does ball start falling to earth
b)what is balls max height
c)How long does it take to hit the ground again?
d)where does the ball hit the ground?

2. Relevant equations
x=Xo + Uxt + (at^2)/2
z=Zo + Uxt + (at^2)/2

r=(0,0,0)
u=Vo(cos45,0,sin45)
a=(0,0,-g)

3. The attempt at a solution

x= Ut
z=cos45t + (sin45t^2)/2

Now I'm stuck lol

 

Yeah, I know that, velocity=0 right? but which equation do I make =0? what do I do after this?

 

We don't have a value for Vo though. That's whats confusing me.

 

Wtf, how would you do that?

 

So the only way to do it is to have an unknown variable still there?

 

So 0= t because anything divided by 0 is 0, correct?