# Find how far the ball drops because of gravity by the time it reaches home plate.

1. Sep 13, 2010

### jessicax07

1. The problem statement, all variables and given/known data

A pitcher throws horizontally a fast ball at 135 km/h toward home plate, which is 18.3 m away. Neglecting air resistance (not a good idea if you are the batter), find how far the ball drops because of gravity by the time it reaches home plate.

2. Relevant equations

vox = vo
y = voy*t+1/2(-g)t2

3. The attempt at a solution

First I changed km/h to m/s and got 37.5. Then I found t and got 0.488s. Then I plugged it into the equation above and got 1.166. It was wrong though. Should it be negative or did I do it wrong?
1. The problem statement, all variables and given/known data

2. Relevant equations

3. The attempt at a solution

2. Sep 13, 2010

### Mindscrape

Hello. I'll preface my response here by saying that you'll probably get more replies to this type of problem if you post in the introductory physics forum. Advanced physics is usually, but not limited to, upper level undergraduate questions.

Yes, your answer should be negative based on the coordinate system you've made. Even the math says it will be negative.

3. Sep 13, 2010

thank you!