# Homework Help: Speedboat Acceleration Question

1. Oct 23, 2008

### aquapod17

1. The problem statement, all variables and given/known data
A speedboat moving at 31.0 m/s approaches a no-wake buoy marker 100 m ahead. The pilot slows the boat with a constant acceleration of -3.5 m/s2 by reducing the throttle.
(a) How long does it take the boat to reach the buoy?
______ s
(b) What is the velocity of the boat when it reaches the buoy?
______ m/s

2. Relevant equations
a = (vf-vi)/t
vf = vi + at
d = vit + (1/2)at^2

3. The attempt at a solution

I keep getting an incorrect answer, but this is what I have been doing.
100 = 31t + (1/2)(-3.5)t^2

2. Oct 23, 2008

### aquapod17

Nevermind I got it! How do you delete threads. I feel really bad leaving this up here when I figured it out myself, but I don't know how to delete!!

3. Oct 23, 2008

### tiny-tim

Hi aquapod17!

You can't delete, you can only do a "never mind" post

but it's ok … lots of members do that …

I think having to type it out for PF actually helps to make the question clearer!