Calculate the force required to pull a copper ball of radius 3.00 cm upward through a fluid at the constant speed 7.00 cm/s. Take the drag force to be proportional to the speed, with proportionality constant 0.950 kg/s. Ignore the buoyant force.

Answer 1

Required force
F = M g + k V

k = 0.950 kg/s

M = (copper density)*(4/3) pi R^3
(make sure it is in kg)
g = 9.8 m/s^2
V = 0.07 m/s
R = 0.03 m
Do the numbers