# Homework Help: Free fall problem w/rocket

1. Sep 14, 2009

### cwalden91

1. The problem statement, all variables and given/known data
During launches, rockets often discard unneeded parts. A certain rocket starts from rest on the launch pad and accelerates upward at a steady 3.30 m/s^2. When it is 235 m above the launch pad, is discards a used fuel canister by simply disconnecting it. Once it is disconnected, the only force acting on the canister is gravity. (air resistance can be ignored). How high is the rocket when the canister hits the launch pad, assuming that the rocket does not change its acceleration? What total distance did the canister travel between its release and its crash onto the launch pad?

2. Relevant equations
Vx=Vox+axt
X=Xo+Voxt+1/2 axt2
Vx2=Vox2+2ax(x-xo)
x-xo=[(vox+vx)/2)t

3. The attempt at a solution

2. Sep 14, 2009

### Chewy0087

okay so you know that it accelerates at a steady 3.3m/s^2

so this equation you have here;

Vx2=Vox2+2aS

so here, final velocity^2 = initial velocity^2 + 2 * acceleration * distance travelled, right?

so how about for a start you can find out the speed the canister (and the rocket) were travelling when it reaches 235m.

you have the initial velocity, acceleration and distance, so work out the final velocity and then think about what that means when it's released, and gravity acts on it! (hint: it has to slow down to 0 m/s before it starts falling!)