# I'm lost. Help?

1. Feb 15, 2009

### joseg707

1. The problem statement, all variables and given/known data
A carton is given an initial speed of 3.0 m/s up a 22.0 degree plane. a.) How far up the plane will it go? b.) How much time elapses before it returns to its starting point? Ignore friction.

2. Relevant equations
F=ma

3. The attempt at a solution
I have no clue. If someone could point me in the right direction and try to explain what's going on I would very much appreciate it.

2. Feb 15, 2009

### joseg707

I've been trying to figure it out. I know I'm supposed to break it into 2 equations, but I don't know how to express the 3.0 m/s velocity in the x equation.

$$\sum$$Fx=mg*sin$$\theta$$=max

$$\sum$$Fy=FN-mg*cos$$\theta$$=may=0

Is that right? If it is I still don't know where to go from here

3. Feb 15, 2009

### jgens

Use the equation vf^2 = vi^2 + 2(a_x)(s).

4. Feb 15, 2009

### joseg707

But I don't know the time, nor the acceleration.

5. Feb 15, 2009

### jgens

You have both the initial and final velocities so all you need right now is the acceleration in the x direction, which you can find by using mg = Fncos(theta) and a_x = gsin(theta).

6. Feb 15, 2009

### joseg707

Oh, ok. Now I get it. You put an (s) in the equation which threw me off. I found the distance and the time it took to reach the max point, but how do I get the total time? Should I just double the time it took to get to the highest point?