Calculate the force required to pull a copper ball of radius 3.50 cm upward through a fluid at the constant speed 6.00 cm/s. take the drag force to be proportional to the speed, with proportionality constant 0.950 kg/s. ignore the buoyant force.

F = 15.75 N

Explanation:

given,

radius of copper ball = 3.50 cm = 0.035 m

constant speed = 6 cm/s = 0.06 m/s

proportionality constant = 0.950 Kg/s

mass of the ball

m = ρ V

now, net force acting

F = m g + k v

where k is the proportionality constant.

where density of cooper ball = ρ = 8.92 x 10³ kg/m³

       F = 15.75 N

it is given that trillions of microbes make up to 1% to 3% of the body mass.

let's take average of this percentage: 2%

consider the average mass of the human body as 70 kg.

then, trillions of microbes would have mass  

therefore, 100 trillion micro-organisms would weigh:

this is an approximate value and could change depending on the mass of the human body and percentage of the microbes present in it.

average mass per microorganism =