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.