# Homework Help: Football, time in air/distance

1. Dec 14, 2008

### Neliel06

1. The problem statement, all variables and given/known data
To get the maximum range, a football kicker kicks a football (at ground level) at an angle of 45degrees. The initial speed of the football is 20 m/s.

a. How long is the football in the air?
b. How far up-field does the football hit the ground?

2. Relevant equations

3. The attempt at a solution

Well originally i thought, i must use X=Xo+1/2(V+Vo)t
to get the time, but that requires X, which is also asked for and not given.
So then i tried getting X. So i used Rmax= Vo^2/g
20/9.8=40.8m
And i also needed V. so i used V^2=V0^2+2a(X-X0)
and got V=34.6 m/s

I plugged those in as X and V and got time=1.5 seconds

However, i only got partial credit, so i don't know where i went wrong
1. The problem statement, all variables and given/known data

2. Relevant equations

3. The attempt at a solution

2. Dec 14, 2008

### rl.bhat

Time of flight = 2V_0*sin(theta)/g