What conditions must be met in order for work to be done? Check all that apply.
A. The output force must be greater than the input force.
B. The applied force must make the object move.
c. At least part of the applied force must be in the same direction as
the movement of the object.
D. The work must be greater than the momentum.

when insulating materials rub against each other, they may become electrically charged . electrons , which are negatively charged, may be 'rubbed off' one material and on to the other. the material that gains electrons becomes negatively charged. the material that loses electrons is left with a positive charge.

the independent variable, or the one that is intentionally manipulated is the speed.

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 =