1. Mar 3, 2010

### SoConfused__

1. The problem statement, all variables and given/known data
Jack went up a hill to fetch water. Jack fell down and rolled down the hill accelerating at 0.65 m/s^2 down. If he rolled 11m down the hill in 3.7s, with what velocity was he moving when he fell?

2. Relevant equations
a = v2 - v1/t
v2 = at + v1

3. The attempt at a solution
(0.65m/s^2)(3.7s) + 11
= 13.5 m/s.

I solved for v2, the velocity when he reached the bottom of the hill.
What am I doing wrong? Am I supposed to be looking for something else, not v2?
Even if I solved for v1, I would get a negative answer.

As usual, I am so confused. :yuck:

2. Mar 3, 2010

### xcvxcvvc

try this
$$R(t) = \frac{1}{2}at^2+v_it+R_i$$
$$v_i = \frac{R(t) - \frac{1}{2}at^2-R_i}{t}$$

3. Mar 4, 2010

### SoConfused__

That confuses me even more. What does R stand for?

4. Mar 4, 2010

### PhanthomJay

what's that 11, that's a length unit, not a speed unit.
you are supposed to be looking for the initial velocity when he fell.
and what would the negative sign imply?