Which is the best example of forces acting in the same direction

Getting someone to help you push your car out of a snowdrift.  You both get on the same end of it and push in the same direction.  Another beautiful example is a Tug-o-War, where you might have 50 people (!) all exerting force on the rope in the same direction.

i already answered it by 34/s

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 =