Bottle Rocket Lab Homework: Calculating Initial Velocity

[lacrosselem]

Homework Statement

In class we made rockets out of 2L bottles and launched them using pressurized water.
The angle that ours went at was 50 degress. Height was 26m. Hangtime 5.18s
acceleration 3.8m/s2 and the mass of the rocket was .52kg

Homework Equations

I am trying to find the initial velocity of the rocket.
vi=vf-at
only problem with that is that I don't have the final velocity either.

The Attempt at a Solution

I honostly have no idea where to start. I have no clue. Help please!
Thanks!

 

[Redbelly98]

Homework Statement

In class we made rockets out of 2L bottles and launched them using pressurized water.
The angle that ours went at was 50 degress. Height was 26m. Hangtime 5.18s
acceleration 3.8m/s2 and the mass of the rocket was .52kg

Homework Equations

I am trying to find the initial velocity of the rocket.
vi=vf-at
only problem with that is that I don't have the final velocity either.

It looks like you are studying motion with constant acceleration. We can do the problem by ignoring air resistance, but I suspect that is not really valid for a 2L plastic bottle going through the air.

If vf is the velocity when the bottle hits the ground, it would equal -vi. Also, where do you get that the acceleration is 3.8 m/s^2?

The Attempt at a Solution

I honostly have no idea where to start. I have no clue. Help please!
Thanks!

p.s. bumping your post hinders getting a response at our forum, since it creates the impression that your post has been replied to already and then people are less likely to bother reading your question.