Aerodynamics

Experiments in Aerodynamics

Experimentally locating the Centre of Pressure and
the Centre of Mass of a simple system
List of Materials
The equipment needed for these experiments can be rounded up from a variety of sources and is quite inexpensive. Some wood, a pencil, a tack, and a set of masses or weights is all that is required. A small household room fan is also required. Not shown, but helpful, is a supply of elastic bands, some masking tape, and "fins" of assorted sizes.
Procedure
The objective here is to find the point at which the system balances as the mass and the "fin" are placed in various locations.
  1. Set up the pieces as shown.
  2. Move the pencil to the point at which the system balances.
  3. Note the mass and its position.
  4. Remove the mass and replace it with another mass at the same location. Re-balance the system.
  5. Note the mass and its position.
  6. Repeat the process for several more masses.
  7. In collaboration with other members of your class, make a general conclusion relating the size of the mass and the location of the centre of mass .
Procedure
The objective here is to find the point at which the system ceases to rotate when subjected to air pressure from the side. A common household fan is used to generate the required air pressure.
  1. Replace the pencil with a push-pin. The system will need some "hands-on" assistance during the experiment to balance it on the pin, and to allow it to rotate freely.
  2. Move the push-pin until the point at which the system does not tend to rotate is located. This is called the center of pressure.
  3. Note location of the "fin" when you find the center of pressure .
  4. Move the fin and repeat the experiment. HINT: an elastic band will hold the fin upright if it tends to fall over.
  5. In collaboration with other members of your class, make a general conclusion relating the position of the fin and the location of the center of pressure.

Key

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