A positively charged particle Q1 = +15nC is held fixed at the origin. A second charge Q2 of mass m = 9.5g is floating a distance d = 25cm above charge Q1. The net force on Q2 is equal to zero. You may assume this system is close to the surface of the Earth.

Calculate the magnitude of Q2 in units of nanocoulombs.

Explanation:

Given

charge on the fixed particle,

mass of the second charge,

distance between the fixed charge and the floating charge on the top,

where:

permittivity of free space

g = acceleration due to gravity

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 =