# Physics

Calculate the force required to pull a copper ball of radius 2.00 cm upward through a fluid at the constant speed 9.00 cm/s. Take the drag force to be proportional to the speed, with proportionality constant 0.950 kg/s. Ignore the buoyant force.

Forcedrag=k v
= .950kg/s * .09m/s= ? joules

but the book says the answer is 3.01 N up?

Total force required = Weight + drag = (4/3) pi R^3 * density * g
+ (0.950) kg/s * 9*10^-2 m/s

Use g = 9.8 m/s^2,
R = 2*10^-2 m,
and density = 8.92*10^3 kg/m^3

AHHH!
thank you SO much.
can i ask you how you got the
"weight" part of the equation?

Weight = Mass * g = Volume*density* g

The answer will be in Newtons, by the way

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