Ping Pong Parachute Physics
How ping pong parachute works
Parachutes work by creating air resistance, or drag, which, in turn, slows the speed at which an object falls at.
If you imaging dropping a ping pong ball and a CD at the same time from the same height, you will notice that the CD will fall slower than the ping pong ball, given that the CD falls completely flat. The greater cross-sectional area of the CD causes greater air resistance and a slower terminal velocity.
The importance of cross-sectional area to the speed that two objects fall at is also demonstrated by the use of a parachute. An parachute increases the cross-sectional area of the falling object it is attached to and increases the amount of air resistance which the object creates.
Once the parachute is opened, the air resistance overtakes the downward force of gravity. The net force and the acceleration on the falling object attached t the parachute is upward. An upward net force on a downward falling object would cause that object to slow down.
Because ping pong parachute is heavily dependent on the time aloft for the ping pong ball, putting a lot of effort into designing the best possible rocket won’t ensure your success.
That said, however, it is important to allocate some resources to optimizing the stability, weight, and deployment mechanism for your rocket.
For more information on how to do so, check out this post.
D = Drag, which is the upwards force acting upon a falling object.
C = Drag Coefficient, which is a constant number, usually between 0.4 and 1.0.
p = Density of the air.
A = Cross-sectional area of the falling object.
v = The speed of the falling object.
vt = The terminal velocity, or highest speed, that the object falls at.
W = Downwards force acting upon an object.
m = mass of the falling object (in kg).
g = Gravitational Acceleration (-9.8 m/s^2).
To achieve the best results, you want to maximize drag using this equation:
To achieve the best results, you want to minimize the downwards force acting upon the ping pong ball and parachute. According to the following equation, reducing the weight of entire system will accomplish this goal.
To extend the time it takes for the ping pong ball and parachute to descend, you want to reduce the terminal velocity of the device.