Retarding and drag force

[Joy Li]

internet the formula shows as this: Vt=squs of(2W/Cd.A.p) >> where as Vt is terminal velocity. W is weight. Cd is the coeficient of >> the object mass, A is the frontal area of the affect area, p is the air >> density. >> Can't it be used to find out the terminal velocity?. Is that right??? To find an object's terminal velocity from free falling.

[FizziksGuy]

That formula only works for a specific object with a specific shape, and doesn't take into account some other factors -- it's an approximation.  It's a reasonable model for certain objects, but all models have limits.

 

To better answer your questions, it'd be helpful if you could elaborate on what you're trying to do... are you trying to prepare for an AP physics exam, are you trying to find the terminal velocity of an unknown object, are you trying to design an object with minimal drag?  Understanding what you're trying to do will help tremendously in answering your question to a higher level of satisfaction.  There are entire courses (and even fields of study) centered around understanding an object's terminal velocity and drag/retarding forces, and knowing what you're trying to accomplish will help tremendously in narrowing down the answer.