
physics acceleration
A fox is chasing a bunny. The bunny is initially hopping east at 9 m/s when it first sees the fox. Over the next half second the bunny changes its velocity to west at 13 m/s and escapes. What was the bunny's average acceleration (magnitude and direction) during this halfsecond interval?
______________m/s^{2}
What equation is used and how is this set up?
I've tried drawing this and I have figured out 22m/s^{2 and he is heading west but the 22 was wrong do I need to do something
with the half second? }

Re: physics acceleration
I would let due east be the positive axis of motion, hence:
$\displaystyle \bar{a}=\frac{\Delta v}{\Delta t}$ where:
$\displaystyle \Delta v=v_fv_i=13\frac{\text{m}}{\text{s}}9\frac{\text{m}}{\text{s}}$
$\displaystyle \Delta t=\frac{1}{2}\text{s}$

Re: physics acceleration
$\displaystyle \vec{a} = \frac{\vec{v_f}  \vec{v_i}}{\Delta{t}}$.
If we set up our coordinate system such that east is positive and west is negative, then
$\displaystyle \vec{a} = \frac{13 \frac{m}{s}  (9 \frac{m}{s})}{\frac{1}{2} s} = 44 \frac{m}{s^2}$. The  sign indicates that the bunny is accelerating west.

Re: physics acceleration
I've input 22 and 44 and both were incorrect. Thanks guys I'm still working at it

Re: physics acceleration
If you are asked for the magnitude and direction, then the magnitude of the average acceleration is 44 m/sē and the direction is west.