# Projectile Motion Demonstration

This applet demonstrates projectile motion. Each point traces out the path of a ball falling in a vacuum. Each time the ball hits the ground (the x-axis) the ball's momentum decreases by 20%. This corresponds to a value of .8 for the bounce coefficient, which is reasonable for most real balls.

In this window, there is air resistance or drag. The force on the ball is represented by

F = mg - bv

where g is -9.8 m/s, and b is a positive number that increases with the amount of friction. The friction coefficient b is set to 0.2 in this case, and the bounce coefficient is set to unity, so that all the decrease in height is due to air resistance.
• Try the default settings and watch the particle's path. Notice how the curve is noticeably shortened from a parabola.
• Drop a particle from a height. Watch it as it falls. If the object stops accelerating and falls at a constant pace, then it has reached terminal velocity . How high do you have to put the particle to observe this effect?

Instructions
• Put in values for the original position and velocity.
• Click "New Particle" to make it go.
• To clear the screen, click "Remove All."
• To scroll around, click the buttons on the edge of the graph.
• To set the viewing options, right click on the graph, then click "Settings"