# Cannon Balls

 Applet by Fu-Kwun Hwang

Instructions
In order to change the position of cannons:

1. Click on the left cannon at the blue dot and drag it up and down.
2. Click on the right cannon at lower right corner and drag it left and right.
3. Both cannons will adjust their angles in order to aim at one another.

In order to change the initial velocity of cannonball:

1. Click the red arrow and drag it left/right or up/down.
2. The length of the red arrow represents the displacement of the cannonball in one second (under no gravity). As long as the velocity is large enough the cannonballs will hit each other.

Click the right mouse button to continue.

If the difference in height is h, and the difference in the horizontal distance is w, then what is the requirement for the velocity v1, v2 that must be met in order for the cannonballs to strike one another?

Want to know the reason? Select the show checkbox to show the trajectory of both cannonballs when there is no gravity and see the effect of gravity on the cannonball (yellow line).

Pausing the animation:

1. Press the left mouse button to pause; release it to continue.
2. If you click on the right mouse button, then you will need to click it again to continue.
3. What if you click right mouse button, then press the left mouse button?

Try it! You will find the answer.