Terminal velocity

[Unkown]

Hey, i m doing my EE in physics. So my topic is how does the shape of the parachute affect the terminal velocity reached by the falling object. My independent variable is the shape of the parachute. Dependent is time taken by the parachute to reach its terminal velocity and my controlled variables are wind, height, mass of the object and the material of the parachute. So here is my doubt that how can i find the point at which the terminal velocity of the parachute is reached?

[Emmi]

Your best bet for actual velocity measurements would be to use some sort of a speedometer or other velocity-measuring device. You can either attach the device to the parachute (account for it in your calculations), or to use a speedometer that is handheld that you point at the object as it falls. Either way you'll need a space that will allow you plenty of vertical room. You can then use graphing software or another program to help you get physical data that you can use for your EE.

[Guest Positron]

If you're really into it, you could build a wind tunnel and see how fast the airflow must be for the parachute to "hover" at a constant altitude. You'd need a tube made out of some see-through material + a motor & propeller + an anemometer (device to measure the speed of airflow). This way you could get good measurements, but obviously would take more effort than the other method. BTW, you might need to define your independent variable more precisely - "shape" is vague and could mean countless different things.

[Andy Sebastian]

If you have neither a speedometer nor access to a wind tunnel, you can rig a camera with a LoS perpendicular to the parachutes' descent to logs their trajectories, and use a graphing program such as logger pro that can plot data points from a video to graph distance against time, and ergo deduce the time and magnitude of terminal velocity.

What exactly is your research question?

Edited July 3, 2014 by Andy Sebastian