Force of 7 N acts on an object. The displacement is, say 8 m, in
the direction of the force
(Fig. 11.3). Let us take it that the
force acts on the object through
the displacement. What is the
work done in this case?

Explanation:

Given

Force (F) = 7 N

Displacement (d) = 8 m

work done (W) = ?

We know that

W = F * d

= 7 * 8

= 56 J

The work done in this case is 56 Joule.

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 =