# Homework Help: Finding distance with velocity, Uk

1. Oct 23, 2007

### habs.fan

1. The problem statement, all variables and given/known data
An airplane makes a belly landing at 80km/h (I've converted to 22.22222m/s), the coefficient of kinetic friction between it and the runway is 0.60. How far does the airplane slide on the runway?

2. Relevant equations
acceleration = [sine(x) - (Uk)(cos(x))] x gravity (I used this formula for an incline question)
V2$$^{}2$$ = V1$$^{}2$$ + 2ad

3. The attempt at a solution

I've tried using the acceleration = sinex ... formula to solve for the acceleration of the airplane, using an angle of 0 because this is the formula I used for an incline question. I found the acceleration was -5.88m/s/s, then plugged that in to the second formula, which yielded me a distance of 1.9m that the airplane travels...which doesn't really make sense to me:
0 = 22.2 + 2(-5.88)(d)
d = 1.9m
Have I done something wrong, or is there an easier formula to use that I haven't come across in my class?

2. Oct 23, 2007

### pooface

You didn't square the initial velocity.

3. Oct 23, 2007

### habs.fan

oh my...thanks