PDA

View Full Version : Terminal Speed


GingerBread27
Oct2-04, 02:41 PM
What is the terminal speed of a 6.5 kg spherical ball with a radius of 3.0 cm and a drag coefficient of 1.50? The density of the air through which the ball falls is 1.2 kg/m3.

I used vt=sqrt((2Fg)/(CpA)). Where Fg is force of gravity, C is drag coeff., p is air density , and A is cross sectional area. When I plug in the numbers I get the wrong answer. I used 1.5 as C, 1.2 as p, 9.8 as Fg, and (9*pi) as a (area of circle-pi*r^2). What am I doing wrong.

freddy
Oct2-04, 02:44 PM
I think you need to convert your radius to meters.

GingerBread27
Oct2-04, 02:53 PM
I forgot to convert lol but that doesn't help, answer is still wrong.

GingerBread27
Oct2-04, 03:19 PM
Never Mind Figured it Out :)

Clausius2
Oct2-04, 04:13 PM
Your expression hasn't got units of velocity.

I think you have forgotten to include the sphere mass in Fg.