What are the period and (constant) speed of a person on a carousel if the person has an acceleration magnitude of 0.80 m/s2 (direction is toward the center) when she is standing 4.0 m from the axis? (b) what are her acceleration magnitude, and speed if she then moves in to a distance of 2.0 m from the carousel center and the carousel keeps rotating with the same period?

part a)

Centripetal acceleration is given as

Now time period is given as

constant speed is given as

part b)

now when she is at radius r = 2 m

centripetal acceleration is given as

now the linear speed is given as

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 =