What is the law of inertia for rotating systems in terms of angular momentum?

Explanation:

The law of inertia states that if an object is in motion will remain in motion unless an external force is applied to it.

law of inertia for the rotating system in terms of angular momentum states that the angular momentum of a system will remain the same unless an external torque is applied to the system.

External Torque either increases or decreases the angular velocity thus changing angular momentum.

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 =