# 2D Kinematics Problem dealing with acceleration

1. Feb 14, 2013

### Element1674

1. The problem statement, all variables and given/known data
" An airplane turns slowly for 9.2s horizontally. The final velocity of the plane is 360km/hr [N]; the average acceleration during the turn is 5.0m/s^2 [W]. What is the initial velocity of the plane?"

2. Relevant equations
a=ΔV/t

3. The attempt at a solution
at=Δv
(5.0m/s^2[W])(9.2s)=Δv
46m/s[W]=Δv

...then from here I get stuck. I know the horizontal component of the plane at the end (final) is 0 and the vertical component (final) is 360km/hr, but this doesn't help me find any obvious solution.

2. Feb 14, 2013

### haruspex

I assume you mean EW, NS, not horizontal and vertical.
You have successfully calculated the change in velocity (a vector), and you know the final velocity, another vector. You are trying to find the initial velocity, a third vector. What, as vectors, is the relationship between the three?

3. Feb 15, 2013

### Element1674

I think I have it!
ΔV=Vf-Vi
Vf-Δv=Vi

I know the x and y components of each Δv and Vf so I set up 2 separate equations:
Vfx-ΔVx=Vix
(Same idea with y)

Then use Pythagorean with Viy and Vix to find Vi, find the angle using trig, etc?

4. Feb 15, 2013

### rude man

I have an answer I'm hoping to compare with the result of the thread, if any.

5. Feb 15, 2013

### haruspex

That'll work.

6. Feb 15, 2013

### rude man

Any plans for the acceleration a in direction W?