# Projectile and acceleration of gravity

1. Oct 13, 2008

### armoredfury16

1. The problem statement, all variables and given/known data
During a baseball game, a batter hits a pop-
up to a fielder 86 m away.
The acceleration of gravity is 9.8 m/s2 .
If the ball remains in the air for 6.3 s, how
high does it rise? Answer in units of m.

2. Relevant equations
y=vi(sin theta)t-1/2g(t)^2

3. The attempt at a solution

I'm not even sure I went about this right...I was only able to fill in that equation this much:

y=vi (sin90)6.3-1/2(-9.8?)(6.3)^2

As you can see, I'm pretty clueless as to how to find the height of the ball at it's highest point...

2. Oct 14, 2008

### alphysicist

Hi armoredfury16,

Since the minus sign has been pulled out in front of the 1/2, you don't need it again with the 9.8.

If you want to use that equation, you might try writing it twice--once for the ball reaching the ground, and one for the ball reaching the highest point. What do you get? (In particular, how long does it take for the ball to reach the highest point?)