# Homework Help: Height of bullet at top of trajectory

1. May 12, 2006

### calnpals

Ok guys, I'm stuck on this question I was wondering if you could help me out.

Its actually in 2 parts (2nd part harder than 1st part).

1st part: At what height will a bullet reach if fired at 1000mph straight up (excluding all other forces except gravity)

2nd part: At what angle would a bullet that is shot at 1000mph have to be shot at to have a speed of 100mph at the height of its trajectory, and what height would it reach?

Thanks

2. May 12, 2006

### daniel_i_l

It would be better if you showed some of your work.
Anyway, for the first part you just need a basic kinimatics equation
( V^2 = Vo^2 + 2ax) or you could use energy.
And for the second part, at the height of the trajectory the only speed is along the x-axis and the speed along that axis is the same throughout the whole trip. Does that make it any easier?

3. May 12, 2006

### marlon

How do you start ? What formula's will you use and more importantly why ?

marlon