What would happen if a coil connected to a galvanometer is kept in a fixed position and a magnet is moved (1) towards the coil and (2) away from the coil.

where are the vectors ?

f=ma newton

f=100x2.5=250n

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 =