# Bottle Rocket lab

1. Oct 19, 2010

### lacrosselem

1. The problem statement, all variables and given/known data
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

2. Relevant equations

I am trying to find the initial velocity of the rocket.
vi=vf-at
only problem with that is that I dont have the final velocity either.

3. The attempt at a solution
I honostly have no idea where to start. I have no clue. Help please!
Thanks!

2. Oct 20, 2010

### Redbelly98

Staff Emeritus
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?

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.