# Dynamics Problem in two dimensions

1. Sep 25, 2006

### mst3kjunkie

5. As a science fair project, you want to launch an 800g model rocket straight up and hit a horizontally moving targer as it passes 30 m above the launch point. the rockey engine provides a constant thrust of 15.0N. The target is approaching at a speed of 15m/s. At what horizontal distance between the target and the rocket should you launch

known:
change in x of rocket=change in y of target=0 m
change in y of rocket=30m
mass of rocket=800g=.800kg
Force applied to rocket in x direction=0 N
Force applied to rocket in y direction=15.0 N
velocity of target in x direction=15 m/s

F1y=15.0 N=ma1y
15.0=(.800)a1y
18.8=a1y

This is about as far as I have gotten. How do I make my way to finding the horizontal distance?

2. Sep 25, 2006

### QuantumKing

well, first..the rocket provides a constant thrust of 15N..you forgot to include gravitational forces. (0.8x9.8)..then find the net force, with that, youll find the acceleration of the rocket, then you can find the time it takes to travel 30m...and ill let you do it from there:)

3. Sep 25, 2006

### mst3kjunkie

thank you so much. I completely forgot to take gravitational force into account. This solves my problem.