# Homework Help: Projectile equation help?

1. Sep 17, 2009

### r_swayze

If the vertical component of the velocity is 20m/s and the horizontal component is 30m/s and g = 10m/s^2, how far does the projectile land from its initial launch point?

the answer I got was 120m, is this correct?

heres my method:

use pythagorean theorem to find initial velocity from the vertical and horizontal component

then find the angle of the launch with vx = v0 cos (theta)

then use R = v0^2 / g sin 2(theta) to find range

2. Sep 17, 2009

### rl.bhat

In future it is better to write down your calculations, rather than giving the answer. It saves our time, which we can use to help the other students.

3. Sep 17, 2009

### TheLegace

A rock (volcanic bomb) is launched out of the mouth of a volcano during eruption.
a) At what initial speed would a bomb have to be ejected, at 35 degrees to the horizontal, from the vent at A in order to land at the foot of volcano at B
b) What would be the time of flight?
Delta d x= 9.40 km
Delta d y= 3.30 km
ay= 9.8 m/s ^2

4. Sep 17, 2009